U.S. NAVAL
Flight Surgeon s Manual
Second Edition
1978
Prepared by
Naval Aerospace Medical Institute
and
BioTechnoIogy, Inc.
Office of Naval Research
Contract N00014-76-C-1010
Under the auspices of
THE BUREAU OF MEDICINE AND SURGERY
Department of the Navy
PROPERTY OF THE ARMED FORCES
MEDICAL UBRARY
Tor aide bjr tbs Superintendent of DooomenU, U.8. QoTeraiiwiit Printtnc Offlce, Waahlngton, D.C. aowa
f
■JOINT MEDjc^L^;fjSi-
Project dir^tion by
Editorial Board
Naval Aarospacd Medical Institute
Captain Henry S. Trostle, MC, USN
Capl^in Frank E.^Dully, MC, USN
Commander Rkhard Millington, MC, USN
BioTechnology, Inc.
Manuscript preparation by
James F. Parker, Jr., PhD
Diane G. Christensen
Barbara M. Sheehan
>■•■ r — t
\C>le'2.
mi
FOREWORD
The Navy Medical Department has one primary mission — to provide for the health care
needs of active duty Navy and Marine Corps personnel. We have a proud record of over
200 years performing this mission. That time period has encompassed virtually all the major
breakthroughs in modern medicine. As the practice of medicine has changed, so has the Navy
Medical Department. Health is a complex state encompassing many factors of varying sorts.
Aberrations in the condition of health must be dealt with from a variety of approaches.
Human response to the aerospace environment is complex and has resulted in the
development of a unique medical specialty — aerospace medicine. This specialty includes not
only highly technical man-machine interface problems, but also the whole range of traditional
medical practice. For instance, the time-honored whole man approach to avialSon personnel
includes participation in the medical care of squadron family members. In addition, Fli^f
Surgeons must often function in environments far removed in both distance and time from the
nearest consultant. It is therefore incumbent upon the aerospace medicine specialist to attain
and maintain the greatest possible competence in the entire spectrum of medicine. This is one of
the most difficult challenges in Navy medicine today. Those who successfully meet this
challenge wiU reap a rich harvest of reward in professional growth, command, and career
satisfaction.
This manual represents a continuing effort by fiie Bureau of Medicine and Surgery to
provide the latest information concerning human response to the aerospace environment and to
describe the special occupational requirements of the Flight Surgeon. The loose-leaf format was
chosen to permit revision and updating on a continuing basis. I am pleased to dedicate this
manual to all our Naval Fhght Surgeons — past, present, and future.
W.P. ARENTZEN
Vice Admiral, Medical Corps
United States Navy
Surgeon General
iii
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PREFACE
The duties and responsibilities of a U.S. Naval Flight Surgeon require him to achieve
expertise and maintain proficiency during an era of rapid technological advances in both
medical practice and naval warfare. The man-machine interface becomes an increasingly critical
factor with the ever-increasing sophistication of aviation weapon systems. The complexity and
unforgiving nature of these systems demand that aircrewmen function at maximum physical and
menM efficiency. The Flight Surgeon is primarily tasked with this responsibility. Additionally,
a Fli^t Surgeon manages a medical team which not only is responsible on a day-to-day basis for
the health and well-being of Navy and Marine personnel assigned to squadrons, air wings, and
ships, but which frequently is responsible for the care of their dependents as well. Although a
Flight Surgeon is a specialist trained to treat the unique problems of human response to the
stresses of the aerospace environment, he must also be prepared to respond promptly and
effectively to a variety of medical emergencies which can range from mass casualties resulting
from a fire aboard ship, to the hazards of thermal stress, or to an outbreak of viral illness among
6,000 officers and men living aboard a modern aircraft carrier.
This edition of the U.S. Naval Flight Surgeon's Manual has been written to provide the
practicing Flight Surgeon a compendium of up-to-date, useful, and -readily accessible
information on the aviation envirorunent and the management of naval aviation-related medical
problems. It is designed to augmmt and reinforce the materials presented in the formal courses
of instruction at the Naval Aerospace Medical Institute. These materials were prepared for use
principally by FUght Surgeons, Aviation Medical Examiners, Aviation Medical Officers and
other medical officers performing aviation machine-associated duties. It is not intended to be a
basic guide to aviation or an all-inclusive volume on aerospace medicine. It is envisioned that
this manual, serving as a procedural guideline and ready reference source, will contribute to
continuing excellence of practice by Naval Fhght Surgeons throughout the Fleet.
Future revisions and correction? to this manual wiLL be made by the Naval Aerospace
Medical Institute.
H.S. TROSTLE
Captain, Medical Corps, U.S. Navy
Commanding Officer
Naval Aerospace Medical Institute
V
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ACKNOWLEDGEMENTS
This volume is the result of a team production with each member performing his required
task. No one individual or select group of individuals was responsible. The support of the
Bureau of Medicine and Surgery and the Naval Health Sciences Education and Training
Command was a primary requiremfflit. The cooperation of Joseph P. Pollard, M.D. and
Arthur B. Callahan, Ph.D. of the Office of Naval Research provided a much needed Vehicle to
publish this manual.
With the exception of the contracted services of BioTechnology, Inc., all of the other
multiple tasks necessary for the pubUcation of this manual were accomplished in addition to the
normal duties of each contributor. Special recognition should be made of tiie contributing
authors. T5iey are:
Authors
LCDR Joseph M. Andrus, MC, USN
CDR Don S. Angelo, MC, USN
CDR C.H. Bercier, MC, USN
CAPT O.G. Blackwell, MC, USN
CDR W.A. Buckendorf, MC, USN
CAPT Eugene J. Colangelo, MC, USN
Ms. Jacque Devine
CAPT Frank E. DuUy, Jr., MC, USN
CAPT F.S. Evans, MC, USN
Martin G. Every, MS
CAPT J.E. Felder, MC, USN
CDR Donald E. Furry, MSC, USN
LT James A. Gessler, MC, USN
Mr. James W. Greene
Frederick E. Guedry, Jr., Ph.D.
LT David T. Margraves, MSC, USN
CDR Norman G. Hoger, MC, USN
CDR Gary L. Holtzman, MC, USN
CDR William M. Houk, MC, USN
CAPT Joseph Kerwin, MC, USN
CDR T.F. Levandowski, MSC, USN
LCDR Neil R. Mclntyre, MC, USNR
vii
U.S. Naval Flight Surgeon's Manual
CDR C.H. McAllister, MC, USN
CDR Richard A. Millington, MC, USN
CAPT J.D. Morgan, MC, USN
LCDR L.P: Newman, MC, USMK
CAPT P.F. O'Connell, MC, USN
James F. Parker, Jr., Ph.D.
CAPT Joseph A. Pursch, MC, USN
Ronald M. Robertson, Ph.D.
CAPT E.J. Sacks, MC, USN
CAPT Richard J. Seeley, MC, USN
CDR PhMp W. Shoemaker, DC, USN
LCDR Felix Zwiebel, MC, USN
The essential logistic, clerical, and secretarial support which was vital to the successful
completion of this project was carried out by:
Support Personnel
Naval Aerospace Medical Institute
LCDR L. Charland, MSG, USN
Ms. Carol S. Hernandez
Ms. Alica A. Bourdier
Ms. Patricia A. Sfefl
Ms. Linda M. Kemp
Ms. Charlotte M. Bennett
Ms. Mary Dee Luff
Ms. Diane L. Early
Ms. Marlene Townsend
Ms. Pat Thomas
Naval Aerospace Medical Research Laboratory
Mr. Robert C. Barrett
Mr. Stanley K. Sulcer
Bureau of Medicine and Surgery
Ms. Linda Roth
BioTechnology, Inc.
Ms. Janet Y. Jones
Ms. Laura S. Bombere
Ms. Betty J. Price
The efforts of all who contributed to this Second Edition are gratefully acknowledged.
TABLE OF CONTENTS
Page
Chapter 1
Physiology of Flight l'^
Chapter 2
Acceleration and Vibration .
Chapter 3
Vestibular Function • ^"^
Chapter 4
Space flight Considerations » . . 4-1
Chapter 5
Intemjd Medicine .5-1
Chapter 6
Psychiatry . 6-1
Chapter 7
Neurology ■ .7-1
Chapter 8
1 ft!
Otorhinolaryngology
Chapter 9
Ophthalmology ^'^
Chi«pter 10
Dermatology ■ • '^^'^
Chapter 11
Venereal Disease ^^'^
Chapter 12
19 1
Dentistry • • '^''"^
Chapter 13
Medical Department Personnel • • l^"!
U.S. Naval Flight Swgeon's Manual -
Chapter 14 '
Aviation Medicine with Fleet Marine Forces 14-1
Chapter 15
Shipboard Medicine 15-1
Cha,pter 16
Disposition of Problem Cases , 16-1
Chapter 17
Aeromedical Evacuation 17-1
Chapt^ 18
Medication and Flight 18-1
Chapter 19
Alcohol Abuse 19-1
Chapter 20
Fatigue 20-1
Chapter 21
Thermal Stresses and Injuries 21-1
Chapter 22
Toxicology 22-1
I ■
Chapter 23
Emergency Escape from Aircraft 23-1
Chapter 24
Aircraft Aeddent Investigations , ,24-1
Chapter 25
Aircraft Accident Survivabihty . . 25-1
■■ ,1;
Chf^ter 26
Aircraft Accident Autopsies 26-1
Appendix A
An Historical Chronol(^ of Aerospace Medicine in the U.S. Navy A-1
Appendix B
Aerospace Medicine Billets B-1
X
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CHAPTER 1
PHYSIOLOGY OF FLIGHT
The Atmosphere
Respiratory Physiolo^
Hypoxia
Dysbarism
References
Bibliography
The Atmosphere
The atmosphere of Earth can be tJiou^t of as an oeean of gases composed primi^^^
nitrogen and oxypn fe whieh are scattered small amounts of other gasefi and impurities, Just a»
a column of water exerts a force or weight per unit area, the column of air above a specific
point exerts a pressure (force), which usually is expressed in millimeters of mercury per square
inch. Table 1-1 presents many, though not all, of the units of pressure measurement in common
use. This table includes both altitude measures and sea water depth measures.
The relationship of pressure and temperature changes produced hy flie fo|ce of the colutnti
of air is presented in TaMe 1^2, from sea level to 100,000 feet in incremenii of 1000 feet, in
both English and metric equivalents. The specific composition of the gaseous mixture at sea
level is presented in Table 1-3. These fractional concentrations remain relatively constant to the
outer hmits of the atmosphere.
The atmosphere can be divided into the inner atmosphere, from sea level to apptoximatfely
600 miles, and the exosphere, which extends from 600 to approximately 1200 miles, the
approximate outfr Hmit. The inner atmosphere can be further divided into the following layers
or zones:
1. The troposphere, extending from sea level to the tropopause, the point at which
temperature becomes constant. This ranges from 30,000 feet in the polar regions to
about 56,000 feet in the equatorial region. In the troposphere occur the ^atest changes
in moisture content, temperature, and convection currents (winds). The greatest
pressure changes also are found in this region, which contains three-quarters of the
atmosphere mass.
1-1
U.S. Naval Flight Surgeon's Manual
Table 1-1
Equivalent Pressures, Altitudes and Depths
12
o
2 6
25
20
10 -
300
600
100- •
lOiJxIoS— OyO
9x 10*
8 X 104
2 X 10*
10''
r
10- -3
3x10* 30-
40-
50-
60-
100;
-20Q. 7
1 s
<
E _
20-
300
tIO
6 O
-150.
O
100_
0-M) — 1
(Billings, 1973b).
1-2
Physiology of Flight
Table 1-2
Altitude-Pressure-Temperature Relationships
Based on the U.S. Standard Atmosphere
Altitude
Pressure
Temper
ature
Feet X 1 0^
Meters
mm Hg
|3Si
C°
#
0
760.0
14.7
59,0
15,0
1
304.8
732.9
14.2
55.4
13.0
2
609.6
706.7
13.7
51.9
11.0
3
914.4
681.2
13.2
48.3
9.1
4
1,219,2
656.4
12.7
44.8
7.1
5
1,524.0
632.4
12,2
41.2
5.1
6
1,828.8
609.1
11,8
37.6
3.1
1
2,133.6
586.5
11.3
34,0
1.1
8
2,438.4
564.6
10.9
30.5
- .8
9
2,743.2
548.4
10.5
26.9
- 2.8
10
3,048.0
552.8
10.1
23,4
- 4.8
11
3,352,8
502.8
9.7
19.8
- 6.8
12
3,657,6
483.5
9.3
16.2
- 8.8
13
3,962.4
464.8
g.o
12.7
-10.7
14
4,267.2
446.6
8.6
9.1
-12.7
15
4,572.0
429.1
8.3
5.5
-14,7
16
4,876.8
412.1
7.9
2.0
-16.7
17
5,181.6
396.7
7,7
- 1.6
-18.7
18
5,486.4
379.8
7.3
- 5.0
-20.6
19
5,791 .2
364.4
7,0
- 8.7
-22.6
20
6,096.0
349.5
6.8
-12.3
-24.6
21
6,400.8
335.2
6.5
-1S.8
-26.6
22
6,705.6
321.3
6.2
-19.4
-28.5
23
7,010.4
307.9
5.9
-22.9
-30.5
24
7,315.2
294.9
5.7
-26.5
-32.5
25
7,620.0
282.4
5.5
-30.0
-34.5
26
7,924.8
270.3
5.2
-33.6
-36.5
27
8,229,6
258.7
5.0
-37.2
-38.4
28
8,533.4
247.4
4.8
-40.7
-40.4
29
8,839.2
236.6
4.6
-44.3
-42.4
30
9,144.0
226.1
4.4
-47.8
-44.4
31
9,448,8
216.1
4.2
-51.4
-46.3
32
9,753.6
206.4
3.9
-54.9
-48.3
33
10,058.4
197,0
3.8
-58.5
-50.3
34
10,363.2
187.9
3.6
-62.1
-52,3
1-3
U.S. Naval Flight Surgeon's Manual
Table 1-2 (Continued)
Altitude-Pressure-Temperature Relationships
Based on the U.S. Standard Atmosphere
Altitude
Pressure
Temperature
Feet X 1 0^
mm Hg
psi
C"
35
10,668.0
179.3
3.5
-65.6
-54.2
36
10,972.8
170.9
3.3
-69.2
-56.2
3?
1 1 ,277.6
162.9
3.2
-69.7
-56.5*
38
1 1,582.4
155.4
3.0
-
-
39
1 1,887.2
148.1
2.9
-
-
An
40
12,192.0
141.2
2.7
-
-
A 1
1 2;496.8
134.5
2.6
— '
-
12,801 .6
128.3
2.5
—
-
13,106.4
1 22.8
2,4
-
AA
13,411.2
116.6
2.3
—
-
AZi
40
13,716.0
111.1
2.1
—
-
46
14,020.8
105.9
2.0
—
-
4/
14,325.6
100.9
1.9
—
-
AO
1 4,630.4
96.3
1.9
—
-
AQ
4y
14,935.2
91.8
1.8
—
-
oU
1 5,240.0
37.5
1.7
—
-
Si
15j544.8
83.4
1.6
-
-
52
1 5,849.6
69.5
1.5
-
-
53
16,154.4
75.8
1.5
—
-
54
16,459.2
72.3
1.4
-
-
55
16,764.0
68.9
1.3
56
1 7,068,8
65.7
1.3
-
-
57
17,373.6
52.6
1 9
58
17,678.4
59.7
1.2
m
17,983.2
56.9
. 1.1
60
18,288.0
54.2
1.0
61
18,592.8
51.7
0.9
62
18,897.6
49.3
0.9
63
19,202.4
46.9
0.9
64
19,507.2
44.8
0.8
65
19,812.0
42.7
0.8
66
20,116.8
40.7
113.4
67
20,421.6
38.8
108.1
68
20,726.4
37.0
103.1
69
:
21,031.2
35.3
98.3
'Temperature rHmains nearly constant above this level up to about 120,000 feet.
1-4
physiology of Flight
Table 1-2 (Continued)
Altitude-Pressure-Temperature Relationships
Based on the U.S. Standard Atmosphere
Altitude
Pressure
Feet X 1 03
Meters
mm Hg
psi
70
21 ,336.0
33.7
93.7
71
21,640.8
32.1
89.4
72
21 ,945.6
30.6
85.3
73
22,250.4
29.2
81.3
74
22,555.2
27.9
77.6
75
22,860.0
26.6
74.0
76
23,164.8
25.4
70.6
77
23,469.6
24.2
67.4
78
23,774.4
23.1
64.3
79
24,079.2
22.0
61.8
■ wb
24,384.01
21.0
58.5
81
24,688.8
20.1
55.8
82
24,993.6
19.1
53.3
83
25,298.4
18.3
50.9
84
25,603.2
17.4
48.6
85
25,908.0
16.6
46.4
86
26,212.8
15.9
44.3
87
26,517.6
15.2
42.3
'•'8S'
26,822.4
14.5
40.8
89
27,127.2
13.8
38.5
m
27,432.0
13.2
36.8
iy?36*8
1v2;6 '
35.1
92
28,041 .6
12.0
35.6
93
28,346.4
11.5
32.0
94
28,651 .2
11.0
30.6
95 •
28,956.0
10.5
29.2
96
29,260.8
10.0
27.9
97
29,565.6
9.6
26.0
98
29,870.4
9.2
25.5
99
30,1 75.2
8.7
24.4
100
30,480.0
8.4
23.3
Temperature
1^'
(from U.S. Naval Flight Surgeon's Manual, 19681.
1, )
1-5
U.S. Naval Flight Surgeon's Manual
Table 1-3
Compositipn of the Dry Atmosphere
Gas
Nitrogen
Oxygen
Argon
Carbon Dioxide
Neon
Krypton
Helium
Hydrogen
Xenon
Volume Percent
78.09
20.95
0.93
0.03
I.SOx 10-3
I.OOx 10-4
5.24x10-*
5.00 X 10-S
S.OOx 10-6
(from U.S. Naval Flight Surgeon's Manual, 1968).
2. The stratosphere, extending from the tropopause to an altitude of approximately
50 miles (13 to 80 km).! In this layer, the temperature remains constant at 55 degrees
Celsius, and there is a very limited quantity of water vapor. Here are found the
high-velocity air masses called the "jet stream." In the upper portion of the stratosphere
the sun 8 radiation causes the formation of ozone (O3). This concentration of ozone is
important m that it absorbs the majority of radiation in the ultraviolet range i ,
(wavelengths shorter than 2900 Angstrom units). ^
3. The ionosphere, extending from roughly 50 to 600 miles (80 to 1000 km) in altitude. In
this layer, strong solar ultraviolet radiations cause a molecular dissociation of oxygen
(O2) and hydrogen (H2) into their charged ionic components. These ionic state
molecules, for which the region is named, separate into two dislnet layers telative to
their atomic weights. This layering produces the reflective qualMes of this zone.
The major atmospheric constituents remain a mixture of nitrogen and oxygen up to
120 km. There, they begin to layer out into an atomi<J4xygen (0) (120 1m to 1200 km) layer
a hehum (He) layer (1000 to 2500 km), and a hydrogen (H) layer above 2500 km.
Respiratory Physiology
Gas physiology is one of the cornerstones of aviation medicine. A great deal of woric has
been done in this field in connection with high-altitude military and civilian aircraft
development as weU as in support of manned space flight. The purpose of this chapter is not to
present a compendium of this information but rather a skeleton upon which an interested Fhght
Surgeon may build throu^ additional reading.
1-6
Physiology of Flight
The principal functions of respiration are to transport alveolar oxygen to the tissues and to
transport tissue carbon dioxide back to the lungs. The process is effected by transporting gases
through the upper respiratory tract and trachea to the alveoli, letting the gases ®f alveoli! and
pulmonary capillary blood reaph equilibrium with eaoh other, transporting the arterial blood t©
tissue, where tissue gases reach equilibrium with arterial gases in the capillaries, and returning
the blood to the lungs to repeat the proeess.
Individual cells within the tissues of the body are basically fluid in composition and, as such,
are essentially incompressible. Pressure appUed uniformly to a tissue surf aee thus is B^adily
transmitted throughout the tissue and to adjoining structures. Changes in the pressure
envirormient, .tii^erefore, do not produce ceUwlar distortion but instead simply change the
pressure of gases contained within the body. The manner in which changes irji,gaa preWE^ affect
the body c w he expressed in terms of the classic laws of gas mechanics.
Boyle's law states that the vohiin« of a gas is inversely proportional to its pressure,
temperature remaiiung constant This means that at 18,000 feet, where the pressure is
approximately half that of ^ea level, a given volume of gas will attempt to expaaxd to twice its
initial volume in ord^r to achieve equilibrium with the surrounding pressure.
Charles' law states that the pressure of a gas is directly proportional to its absolute
temperature, volume remaining constant. The contraction of gas due to temperature change at
ahitude^ however, in no mannw compensates for die expansion due to the corresponding
decrease in pressure.
Dalton's law of partial pressures states that each gas in a mixture of gases behaves as if it
alone occupied the total volume and exerts a pressure, its partial pressure, independent of the
other gases present. The sum of the partial pressures of individual gases is equal to the total
pressure. U#ng thi« lm\ one can csdciilate tihte partial pressure of a gas in a miaLture Simply by
knowing the percentage of concentration in that mixture.
Henry's law states that the weight of a gas absorbed by a given liquid, with which it does not
combine chemically, is directly proportional to the pressure of the gas.
Graham's law states that the relative *ates of diffudoft of gasfes uittder the mm Cdnditions <>f
teiftperature and pressure are inversely proportional to the square roots of the densities of those
gases. 'Gidises with smaller molecular weights will diffuse more rapidly.
The four principal gases of interest in aviation medicine are oxygen, nitrogen, carbon
dioxide, and water vapor.
17
U.S. Nav^Ili^tJuigfqp^l? IMaM
Pulmonary Ventilation i , .
Ventilation is a cyclic process by which fresh air or a gas mixture enters the lungs and
pulmohary air is expelled. The inspired volume is greater than the expired volume because the
volume of oitygen abtotbed by the bloodis gteatef ton ite Tdtt^^^^ dioxide, which is
released from the blstodt Since gas esiebftnge^ oecurs solely in the alveoli and not in the
conducting airways, the estimation of alveola ventilation rate (i.e., the amount of gas which
enters the alveoh per minute) is the most important single variable of ventilation.
Pulmonary ventilation does not occuf evenly throughout the alveoli since normal lungs do
irot behft*e'like perfect mixing chambers, nor is the pulmonary capillary network evenly
distributed throughout the Itings. VentUation, therefore, tttMt beteaaj»|tetf l(|^y(n#y to
the increased or decreased blood flow, or some of the alveoli will be rel AeV uMif < or
over-ventilated. The even distribution of pulmonary capillary blood flow is as important h an
even distribution of inspired air to the alveoli for normal oxygenation of the blood.
Gaseous Diffusion
Respiratory gas exchange in the lungs is accomplished entirely by the process of simple
diffusioii. The direction and ^ount of movement of tiie mijiecules depend upon the difference
in. partial pressure on both sides of the alveolar membiane. Normally, molecular oxygen moves
from a region of higher partial pressure to one of lower partial pressure. The volume of gas
which can pass across the alveolar membrane per unit time at a given pressure is the diffusing
capacity of the lungs.
The diffusing capacity is not only dependent on the difference in partial pressure of the gas
in the alveolar air and puhnonary capillary blood, but it is also proportional to such factors as
the effective surface area of the pulmonary vascular bed. It is inversely proportional to the
average thickness of the alveolar membrane and directly proportional to the solubiHty of the gas
in the membrane. The normal values for diffusing capacity range from 20 to 30 ml
02^a/mm Hg for normal young adults.
Pulmdnary Capillary Blood Flow
Puhnonary capillary blood flow must be adetfuate in Vol«inLe and well disttibuted to M of
the ventilated ^IveoU to insure proper gas exchange. Undei^fjaliliiin itfipawly ventilated alveoli
can become a serious matter during flight when G forces acting on the body result in a
redistribution of pulmonary capillary blood flow. During exposure to positive (+0^) accelerative
forces, the Blood flow is diluted to the lung bases, whereas, during exposure to negative ( G^)
accei^ation, fhellc^is tow|t|i ipM
1-8
Physiology of Fbght
Composition of Respired Air
The major constituents of the atmosphere are oxygen, nitrogen, and water vapor. The rare
gases (argon, krypton, etc.) have not been demonstrated to be biologically significant. In
physiologic gas analysis, these concentrations, if determined, are included in the valu^ reported
for nitrogen.
Atmospheric Air _ . i
In dry air at sea level, the partial pressures of the constituent gases according; to Dalton's law
are:
PO2 = 760 mm Hgx 0.2075= 159.2 mm Hg
PN2 = 760 mm I%x 0.7902 =600,6 nam Hg
PCO2 = 760 mm %^ 0,00(1S = 0.2 BiHi Hg.
Tracheal Air
When inspired air enters the respiratory passages, it rapidly becomes saturated with water
vapor and is warmed to body temperature. The water vapor has a constant pressure of
47 mm Hg at the normal body temperature of 98.6° F, regardless of the barometric pressure.
Aceotdijigly, the sum of the partial pressures of the inspwed gases no longer equals the
b^rome^c pressure, but instead eqaas the barometric pressure minus the water vapor pressure.
Thus, the tracheal partial pressure of inspired gases can be calculated as follows:
Ptr = (PB-47)xFI c
where . . ■ 1''
Ptr = Thetrftchfeal'pSiiSatpreisureofihein^ =..1 '
PB = Barometric pressure
FI = The fractional concentration of the inspired gas.
AlveQlftr Air
The theoretical alveolar (alv) PO2 for any altitude can be calculated if one knows the
barometric pressure and the dry fraction (percentage) of oxygen in the inhaled gas. A constant,
sea-level ventilation rate and a normal metaboUc rate are presumed fot the Uke of simplicity.
With tracheal (tr) PH2O a constant 47 mm Hg, PC02(alv) a constant 40 mm Hg, a barometric
1-9
U.S. Naval Flight SuFgeote's Manual
pressure at 10,000 feet of 523 mm Hg, and a dry fraction of ox^geil of 11 percent, then at
10,000 feet breathing air,
PO2 (tr) = (PB ~ PH2 0 [tr] ) X .21 or
PO2 (tr) = .21 (523-47) = 99.96 mm Hg.
However, in the trattaition from tracheal gas to alveolar gas, the PO2 is reduced, and PCO2 is
increased. The PNg remains the same. Therefore,
P02(alv) = P02(tr)-PC02(alv)
P02(alv) = 99.96mmHg-40mmHg-60mmHg.
Actual measurements of P02(alv) at various altitudes derived from both breathing air and
breathing 100 percent oxygen are presented in Table 1-4. The P02(alv) at 10,000 feet breathing
air was measured to be 61 mm Hg. This drop in PO2 with ascent causes a gradually increasing
hypoxic stimulus to respiration (via the chemoreceptors in the area of the carotid sinus)
resulting in an increased respiratory exchange rate (RER) and an increased P02(alv) over that
calculated. There also is a decreased PCOaCalv). Table 14 can he' used for calcolatioris when
measured data are not available.
Table 1-5 shows measured changes at sea level in the partial pressure of the gases at various
sites in the irespiratory cycle. This is ttlustrated graphically for oxygen and carbon dioxide in
Figure 1-1.
Oxygen Transport
Oxygen is carried in the blood both in simple physical solution and in loose chemical
combination with hemoglobin in the form of oxyhemoglobin. The oxygen transport capacity of
one gram of hemoglobin is 1.36 mi of oxygen. Therefore, the capacity for 100 ml of blood is
about 20 ml of oxygen (presuming normal hemoglobin to be 14.7 gm/ 100 ml) and represents
100 percent hemoglobin saturatiorL Normally, arterial hemoglobin in an individual breathing air
at sea level is 98 percent saturated. When breathing 100 percent oxygen at sea-level pressure, the
hemoglobin becomes 100 percent saturated, and additional oxygen goes into simple solution in
the plasma. The total of additional oxygen so transported is 11 percent greater than normal.
In Figure 1-2, a family of oxygen-hemoglobin dissociation curves is presented. From these
curves it cart be seen that the Mood leaves the pulmGnary capillary bed with the hemoglobin
^OBi- 9®.iperceM satewated. Even if the P02(alv) is reduced by 20 mm Hg, the saturation is
reduced by only three to four percent. In the tissue capillaries, however, a small decrease in
oxygen tension causes changes in the dissociation curve which result in a large quantity of
1-10
Table 1-4
Tracheal Oxygen Pressure, Alveolar Oxygen Pressure, and Carbon Dioxide Pressure in the Alveolar Gas When Breathing
Air and 100 Percent Oxygen at Physiologically Equivalent Altitudes
Breathing air
Altitude
Feet
Sea level
s.«»
tOjOCXl
IJgOOO
xo,oao
ii.ooo
Baro-
metric
pressure
Tracheal
P02
mm of Hg
760
413
j49
J"
mm of Hg
149
112.
100
80
63
57
Alveolar
P02
mm of f/g
103
79
61
46
33
30
Pcoj
mm 5/
40
38
36
33
30
2.8
RER*
o. 8;
o. 87
o. 90
o. 95
1. 00
1.05
Breathing oxygen (loo percent)
Altitude
Ftet
33, 000
36, 000
39, 000
41, 000
45, 000
46, 000
■Baro-
metric
pressure
mm of
ig6
17D
1 48
12.8
III
iq6
Tracheal
P02
mm of Hg
149
113
64
59
Alveolar
P02
♦Respiratory exchange rate (Jjahy 1961).
Table 1-5
Partial Pressures of Respiratory Gases at Various Sites in Respiratory
Circuit of Man at Rest at Sea Level
Sainple
Inspired air. . .
Expired air —
Alveolar air . . .
Arterial blood .
Venous blood,
Tissnes
Gas partial pressure
mm Hg
mm Hg
N2
mm Hg
H2O
mm Hg
158
0,3
596
5-7
lie
31
5^5
47
100
40
573
47
100
40
573
47
40
46
573
47
30
50
573
47
or less
ot mote
Total
mm Hg
760
760
760
760
706
700
nofHi
109
85
64
48
34
30
Pcos
' 0/ Hg
40
38
36
33
30
19
(Carlson, 1565a.)
U.S. Naval Flight Surgeon's Manual
©
®
®
©
SEA level L
INSPIRED
AIR
IN
ALVtOLAR IN
- | ARTERIAL
Alfl
BLOOD
IN
CAflLLARy
BLOOD
AND
TISSUES
<
IN TISSUES AND
VENOUS flLOOD jALVEOLAn
AIR AND
ARTERIAL
BLOOD
IN AIR AT SEA LEVEL
Figure 1-1. Partial pressures oif O2 (above) and GOg (below) in air at sea level
and at various paints within the body (BUlhigs, 1973a).
oxygen being made available to the tissues. The upper section of the dissociation curves
(Figure 1-2A) remains relatively flat through an oxygen tension change of 40 mm Hg; thus,
when the P02(alv) falls from 100 to 60 mm Hg the blood saturation is reduced only by about
eight percent. As the oxygen tension continue to fall, however, an additional reduction of
30 mm llg results in a precipitous dmp in blood saturation to 58 percent. Thus, the
characteristic shape of the dissociation curves accounts for the relatively mild effects of hypoxia
at low altitude and the very serious impairment of function at higher altitudes.
The oxygen-carrying capacity of the blood hemoglobin is also very sensitive to changes in
blood pH (Bohr effect), as illustrated in F^re 1-2B. At an oxygen tension of 60 mm Hg, for
example, at pH 7.2, 7.4, and 7.6, the arterial oxygen saturation is observed to be 84,89, md
94perccnl, respectively. Carbon dioxide is the major determinant of blood pH. In venous
blood, PCO2 is high; accordingly, the pH is low. In arterial blood, the PCO2 is less as a result of
the diffusion of carbon dioxide into the alveoli. The arterial blood, therefore, has a higher pH
and can carry more oxygen at a given alveolar PO2 than would be possible without this change
in pH. In the tissues, the reverse condition exists.
1-12
a
100
z
Ul
>-
X
so
o
z
OBI
60
_i
o
1
10
o
NT
ZO
LlJ
U
(E
lU
0.
0
y
7/ y
"5/ /
Ay
A
B
E Og rt»rh Hg
9
K
(A
U
O
a.
OXYGEN PRESSUft^ "liT?W'W9
Figure 1-2. A, Effect of CO2 on oxygen dissociation curve of whole blood (after
Barcroft). B. Effect of acidity on oxygsU 3il9odBfibn curve of blood (after
Peters & Van Slyke). C. Effect of teinipetalwte. on, oxygen dissociation curve of
Wood (Carlson, 1965b).
, :, ^;,,,.;,'t( ,111 S". , :^-i'iJf - • :. > ji <M IXi.M :id! ^JuuiOTf
Control of Respira'fion r. 1-1 -i-LiiiJ^v: n -.t. - _ -'dji'' iir.
The neural control of respiration is accomplished by neurons in the Teticular fdBtnition of
the medulla. This rhythmic activity is modified by afferent impulses arising from receptors in
various parts of the body, by impulses originating in higher centers of the central nervous
system, and by specific local effects induced by ehsmges'll #i''fife^feal'ismpoitio»n%^
iii(<i«.>«j , -! ,11 M ■ « •»idii.Tt-M--n<>> '
A major decrease in arterial PO2 causes shghtly increased pulmonary ventilation. However,
if the afferent fibers from the chemoreceptive areas are severed, respiration is depressed. Thus,
the direct effect of hypoxia ontherespiratory center itself is depressive, but hypoxia will cause
increased pulmonary veMtilatiG® ivhiBH the-^ateeiftofeeeptor mechanism is intiaet.
1-13
U.S. Naval FU^t Svf^on's Mwiual
A minute increase of about 0.25 percent alveolar carbon dioxide will lead to a 100 percent
increase in pulmonary ventilation rate. Conversely, lowering the alveolar PCO2 by voluntary
hyperventilation tends to produce apnea. From these observations, it may be deduced that
control of respiration appe^rs^o be%f temed primarily by the homeostasis of alveolar PCO2.
Oxygen lack is a rather ineffe«|^ye stimuhis foy ptOmonaiy yeratilation. Ermting (l<W5b)
reports that no increase in pulmonary ventilation occurs with acute oxygen lack until the
alveolar PO2 is reduced to about 65 mm Hg, or at approximately 37,000 to 39,000 feet
equivalent altitude, breathing 100 percent oxygen. Even a reduction of alveolar oxygen to about
40 mm Hg (42,0@P feet eqiaivalent allitude) will only increase ventilation by about one-third of
its normal re^ng v^m. 'We^mmtpi fxiMtomaj ventilation occurring in hypoxia does not
represent a simple reaction to the reduced alveolar oxygen tension.
An increase in oxygen tension will produce minor changes in respiration. Use of 100 percent
oxygen causes an initial slight depression of respiration, followed by moderate stimulation of
breathing. The depression is considered to be caused by the effect of high oxygen tension on the
chemoreceptors in the aortic #nd carotid bodies. The'-sulis^^t sijimilation may be caused by
the irritant action of 100 pprcetit oxygen on pulmonaiy'ft^eilfesl.
Under heavy exercise, maximum pulmonary ventilation can reach 110 to 120 liters per
minute, as compared to a resting rate of six liters per minute. In aviation, however, extremes of
physical activity are not enecSltetered, and mBtaJiolic oxygen consumption seldom exceeds two
or three times the resting rate. On this basis, the provision of oxygen in miUtary aircraft is based
on a maximimi pulmonary ventilation rate of 25 liters per minute.
Hypoxia
Probably the most frequently encountered b^ard in aviation medicine is hypoxia. Records
of early balloon and aircraft flights describe tragedies resulting from hypoxia,'^Be even these
primitive machines had a higher operational t^iling ^ian tlje men aboard them-
Hypoxia was a serious aviation problem in both World Wars and remains a potential threat
mm Hir^Wday's military aviation. Er^neering soittti^iis to the problem have been ingenious.
Considerable money has been expended on training of aviators and on procurement of
equipment to prevent hypoxia. Yet, hypoxic incidents continue to occur, and the Flight
Surgeon should be well-informed concerning thi^ problem,
Itere is a commonly encountered misconception among aviators that it is possible to learn
all of the early symptoms of hypfc^a and then tw» 0m corrective measures once symptoms are
144
noted. This concept is appeate^'becaUse it alldWs all actiori, hfflik pfevesMttW%A#M*ttective, to
be postponed until th^'ft^al occurrence.
Unfortunately, the theory is both false and dangerous. One of the earliest effects of hypoxia
is impairment of judgment. Therefore, even if the early symptoms are noted, an aviator may
disregard them and often does, or he may take corrective action which is actually hazardous,
such as disconnecting himself from his only oxygen supply. FinaUyj at hi^ altitudes, hypoxia
may cause unconsciousness as the first symptom.
These factors must be kept in mind during a Fhght Surgeon's study of hypoxia, during the
indoctrination and refresher training flights in the altitude chamber at an Aviation Physiology
Training Unit, and especially during the Flight Surgeon's diO^ eoritlicf avi2^ti*ln tlie ready
room, sickbay, or clinic.
There are few statistics which tell exactly the number of accidents and fatahties in military
aviation which can be attributed to this problem. Some indication of its seriousness, however,
can be inferred from an Air Force tabulation over a period from January 1970 to
Deceulber 1975 in w^ch there were 40 reported hypoxic in'd^ilttliVTItestf itoGidents occurred in
fighter and attack jet aircraft. In Mlif fefifi^isiSI', i #iiliii^ia*idiatfe4^eitiJt#l'^^^^
been trained to recognize the symfiiite otf ft^^^^pi^^'^^^
altitude. Obviously, crashes have occurred as a result of hypoxia, although accident statistics do
not show this.
Ten of the cases reported by the Air Force occurred while cockpit pressurization was either
not operating properly or was sfectaifei* Ift MilAj^^'tf IK^J'I^^
oxygen dismpUiie (ffn^e part of the pilisl 4li'#fiJli% tf^fKliidtfliit dfeeefl^ fs^tttB'aiftfl^ittfee.
Types of Hypoxia
The amount and pressure of oxygen delivered to the tissues is determined by arterial oxygen
saturation, by the total oxygen-carrying capacity, and by the rate of delivery to the tissues.
Hypoxia, defined as an insufficient supply of oxygen, can result from any one of these factors.
Accordingly, the following classic types of hypoxia'have been distinguished: ■ ' ^
1. Hypoxic hypoxia results from an inadequate oxygenation of the arterial blood and is
caused by reduced oxygen partial pressure. ... , ■
2. Anemic hypoxia results from the reduced oxygen-carrying capacity of the blood, which
msc^ke die to blood loss, any of tbe anemias, ciabwHionojade poii^Wto^ or by dfugs
causing methemoglobinemia. '
1-15
Cf J, pisipj Bli^t Surgeon's Manual
.$tu$t^rtmt ^ifflff w»?Pi<fef '#^^»l*fi@^' m#B3l#ttip^r3y^#i-i^ for example,
Ifta the venoiis paoling eneountered during accebr«ypn.maneuyeri.
A fourth type, histotoxic ft^yj^oajfe, results from an inability of tfie cells to utilize Ihe oxygen
provided when the normal oxidation processes have been poisoned by cyanide. There is no
oxygen lack in the tis^es,. but rather an inutility to use available oxygen, with the result that
the PO2 in the tissues may jse Itighfi t^ian normal. Tb^fpfore,, ijt. is iii^t true h^oxja by the
definition used here.
The most common type of hypoxia encountered in aviation is hypoxic hypoxia. This results
from the reduced oxygen partial pressure in the inspired air caused by the decrease in
barometric pressure. Other types may also affect aircrewraen, such as anemic hypoxia as seen in
carbon monoxide poisoning and stagnant hypoxia resulting during various acceleration profiles.
Types of Onset of Hypoxia
The onset of hypoxia varies with the cause. During ascent to altitude without
supplementary oxygen equipment, the onset of hypoxia is as gradual as the rate of as0f%t. As
sg«p ^ a^ inspiratio%ie< ^i3fi|eted^ <te ^alveo^ tpf^ l^pjpliajsh^ e^ . mthti^@iBy|^d
gase% «nd jimil-arfy, the ptfis^ gases reach a ve^^xapii equilibrium with the alveolar gases, but
the.change in l^pjBp^ . .i^.t . i
In the event of contamination or dilution of oxygen in the mask with some amount of cabin
air, due to either a leaky mask or faulty tubing, onset of hypoxia is intermittent. Moreover, the
siEfigii 0$ iegim^0^i]m;i^ Ih^j^oj^nt of hypoxia develcfuing Ti>fip from one breath to the
depending m lm^fi$^^^i0!lmto, -m^kQ'iy po^pij (whicl^ ti5l«y pause the aperture of a
leak to be temporarily closed, partially open, or completely open). This type of hypoxia onset is
baffling to trace because it is often difficult to validate that a hypoxic incident occurred, much
less to determine the cause.
In the case of a supply hose disconnect or other cause of exposure to ambient s§t, whether
known or unknown, the onset of symptoms wiU be determined by the altitude during exposure.
If such a disconnect is immediately discovered, and if no decompression is involved, one should
hold one's breath while attempting to reconnect, because the alveolar PO2 is higher than the
ambient PO2. Breathing in such circumstances will cause a washout of oxygen from the tissues.
This must be avoided as long as possible;
When rapid decompression occurs, the volume and pressure of alveolar gases become
markedly higher than those of the ambient atmosphere, and sudden expulsion of the alveolar
TJ.S. Naval Flight Surgeon's Manual
gases oGourg . At the end of the resulting involuntary expiration, the normal reaction is to inhale,
and at the end of that inspiration, the alveolar PO2 is in equilibrium with the ambient. The
resulting effects will depend upon the PO2 at the terminal decompression altitude.
Symptomatology
Many observations have been made on the subjective and objective symptoms of hypoxia. A
detailed analysis of progressive functional impairment indicates that the effects of hvpoxia full
into four stages. Table 1-6 summarizes the stages of hypoxia in relation to the altitude o!'
occurrence, breathing air or breathing 100 percent oxygen, and the suterial oxygen saturation.
Table 1-6
Stages of Hypoxia
Stage
Altitude in feet
Arterial oxygen
saturation
Cpercent)
Breathing air
Breathing loo
percent O2
o-io, 000
10, OCXI-I5, CX50
15,000-10,000
10^000-9.3,000
33, 000-39,
39, 000-41, lOO
41, 10O-4J, xoo
4$i 100-46, Sob
95-90
90-80
80-70
70-60
lU.Si Naval Flight Surgeon's Manual, 1968).
Indifferent Stage. There is no observed impairment. The only adverse effe(;t is on
dark-adaptation, emphasizing the need for oxygen use from the ground up during night flights.
Compensatory Stage. The physiological adjustments which occur in tile respiratory and
circulatory systems are adequate to provide defense against the effects of hypoxia. Factors such
as environmental stress or prolonged exercise can produce certain decompensations. In general.
in this stage there is an increase in pulse rate, respiratory minute volumes, systolic blood
pressure, and cardiac output. There is also an increase in fatigue, irritability, and headache, and
a dficreasc in judgment. The individual has difficulty with simple tests requiring mental alertness
or moderate muscular coordination. Table 1-7 dlustrates the compensatory physiological
compensations which occur over a period of 60 minutes on acute exposure to 18,000 feet.
Disturbance StUge. In this st^e, decompressions are inadequate to provide sufficient oxygen
for the tissues, and hypoxia is evident. Subjective symptoms may include headache, fatigue,
lassitude, somnolence, dizziness, "air-hunger," and euphoria. At 20,000 feet, the period of
1-17
U.S. Naval Pligjit Suigepn's Manual
useful consciousness is 15 to 20,jt^pmjBs. In some qases, there are no subjective symptoms
noticeable up to the time of unponseiousness. Objective finding include:
1. Special Senses, Peripheral and central vision are impaired and visual acuity is diminished.
There is weakness and incoordination of the extraocular muscles and reduced range of
accommodation. Touch and pain sense are lost. Hearing is one of the last senses to be
affected,
2. Menial Processes. The most striking ^mptoms of oxygen deprivation at these altitudes
are classed as psychological. These are the ones which make the problem of corrective
action so difficult. InteHectual impairment occurs f|ffly, and the pilot has difficulty
recognizing an emergency situation unless he is widely experienced with hypoxia and
has been very highly trained. Thinking is slow; memory is faulty; and judgment is poor.
3. Personality Traits. In this state of mental disturbance, there may be a release of basic
personality traits and emotions. Euphoria, elation, moroseness, pugnaciousness, and
gross overconfidence may be manifest. The behavior may appear very similar to that
noted in alcoholic intoxication.
4. Psychomotor Functions. Muscular coordmation is reduced and fJie performance of fine
or delicate muscular movements may be impossible. As a result, there is poor
handwriting, stammering, and poor coordination in flying. Hyperventilation is noted and
cyanosis occurs, most noticeable in the nail beds and lips.
Table 1-7
Inspired and Alvoelar Gas Tensions {mm Hg), and Pulmonary Ventilation
at Sea Level, and During an Acute Exposure to 18,000 Feet
18,000 feet
Sea level
5 ninaces
30 minutes
60 minutes
760
380
380
380
Inspiced oxygen tension (fetchtui) . , <
150
70
70
70
lOJ
40
38
36
40
33
30. 6
30
0.83
1. 14
0.55
0.85
Pulmonary ventilation (l./min 3.T.P,S.)
8.48
13.51
II. 50
10.71
Oxygen tension gradient inspired to alveolar
47
30
31
34
(Ernsting, 1965a).
1-18
Phydology of Flight
Critical Stage. In. tihis stage of acute hyppxia, there is almost complete mental and physieal
incapacitation, resulting in rapid loss of consciousness, convulsions, and finally in failure of
respiration and death.
An important factor in the sequences cited aboi^ is the gradual a^kht to altitude where the
individual can come to equilibrium with the gaseous environmentj md physiological
adjustments have sufficient time to: come into play. Tbk occurs in military aviation ©nly in cases
where the aviator is unaware that his oxygen is disconnected or in cases where leaks occur in the
oxygen system, causing gradual dilution of the oxygen with cabin air.
Of greatest concern to a Flight Surgeon is hypoxia resulting from the sudden loss of cabin
pressure in aircraft operating at very high altitudes. Under these conditions, a loss of
pressurization or oxygen supply will cause exposure of the aviator to environmental conditions
so stressful that physiological compensation cannot occur before the onset of unconsciousness.
Time of Useful Consciousness
The time of useful consciousness is that period between an individual's sudden deprivation
of oxygen at a given altitude and the onset of physical or mental impairment which prohibits his
tjddng rational aefion. It represents the time during which the i|idivi4ual can recognize his
problem and re-establish an oxygen supply, iiffllSate a desceiit to Ijjwer altitude, or take other
corrective action.
The time of useful consciousness is primarily related to altitude, but it is also influenced by
individual tolerances, physical activity, the way in which the hypoxia is produced, and the
environmental conditions prior to the exposure. Average times of useful cor-sciousness at rest
and with moderate activity at vaoBous altitudes are shown in Table 1-8. The subjects were
breathing oxygen and produced the hyposic enviromnents by disconnecting their masks.
Billings (1973a) emphasizes that if an individual breathing air is suddenly decompressed, his
time of useful consciousness is shorter than if he had been breathing oxygen (Figure 1-3). The
PO2 in his lungs drops immediately to a level dependent only on the final altitude, rather than
dropping gradually with each breath of air, dependent on lung v"oluine,-dilyiion.of that volume,
and altitude.
Limit Altitudes and Altitude Equivalents <,<
In considering hypoxia, some mammHn limit must be set on Ae^pfly of ttsygen eonsidesid
"adequate" for the purposes of military aviation. Ideally, one would select sea-level conditions as
the bmit and design and construct oxygen supply systems to m aintain them , but this is not feasible
considering the altitudes at which Navy and Marine Corps aircraft are capable of operating.
1-19
U.S. Naval Flight §B*g(teii^ Manual
Table 1-8
Time of Useful Consciousness
BLtjid disconnect (moderate
activity)
Rapid disconnect (sitting
quietly)
13.
18
30
3S
40
6S
5 miantes.
i minutes
I minute . .
45 seconds
30 seconds
18 seconds
II seconds
10 miauces.
3 minutes.
I minute JO seconds.
I minute ij seconds.
45 seconds.
30 seconds.
12. seconds.
(Carlyte, W63).
5S000
SODOD
' 0 ' IP 20 30 40 50 60 70 BO 90
. TIME OF USEFUL CONSCIOUSNESS (sec)
Figure 1-3. Minimum and average duration of effective conBciousness
in subjects following rapid decomprel^dn breathing air (lower curve)
and O2 (upper curve) (BUlings, 1973a; data from Bleckley & Hanifan,
1961).
In detemining a limit altitude, one is actually specifyiiig' the maximum level of hypoxia
tsdiich is acceptable. The Navy NATOPS Manual, General Flight and Operating Instructions,
OPNAV Instruction 3710.7 series, specifies the following limit altitudes for crewmembers
aboard naval aircraft: With one exception, all occupants aboard naval aircraft will use
supplemental oxygen on flights in which Ihe cabin altitude exceeds 10,000 feet.
1-20
Physiplogy of Might
Exception: When all occupants are equipped with oxygen, unpressurked aircraft may ascend to
flight level 250 (25,000 feet). When minimum en route altitudes or an ATC clearance requires
flight above 10,000 feet in an unpressurized aircraft, the pilot at the controls shall use oxygen.
When oxygen is not available to other occupants, flight between 10,000 and 13,000 feet shall
not 4xdeed three houra durMiOQ, tod flight above IS^OOO-fetetis proHSbitedi
I't ■••i'l" r'l
Table 1-9 gives the oxygen requirements for pressurized aircraft flown abttve 10,000 feet,
when cabin altitude is maintained at 10,000 feet or less. The quantity of oxygen aboard an
aircraft before takeoff must be sufficient to accomplish the planned mission. In aircraft carrying
passengers, there must be an adequate quantity of oxygen to protect all occupants through
normal descent to 10,000 feet. "' ' "^M
Table 1-9
Oxygen Requirements for Pressurized Aircraft
• i-y • -•I'll',
Second pilot
Ciew on
Other
duty
occupants
R
R
R
„ J, „ „,,^-
N/A
I
R
R
R
I
I
B.
R
orO
R
O
I
R
R
O
I
I
i
P
P
P
p
Legend :
R— Oxygen shall be readily available.
I-^<D)f|rgeii shall he itime&ibdy kV^laWe. Helmets shall be Wdra with an oxygen mask attached
to one side or an approved quick-donning or sweep-on mask propecly adjusted and positioned
for immediate use. Set oxygen regulator > loo percent and ON.
O — Oxygen shall be used.
P — Pressure suit shall be worn.
(OPNAVINST 3710.7 series)
If loss of pTessurization occurs, a descent shall be made immediately td'fifiyht level where
cabifi dlitiidfe mm be maintained lit, or below, 25^000 f^t, atfd (^xygett shiill be titiUaed
occupants.
When it is observed or suspected that an occupant of any aircraft is suffering the effects of
decompression sickness, the pilot will inlmediateiy descetldi land at the'neatisfilnaitidM
1-21
U.S. Naval PEght Sut^n 's Manual
obtain qualified medical assistance. The person affected may continue the flight only aft' the
advice of a Fhght Surgeon. . ■ ri ;
In pressurized combat and combat training jet aircraft, oxygen shall be used by all
crewmembers from takeoff to landing. Emergency ba^out bottles, where provided, shall be
connected prior to takeoff. Whenever practicable, 100 percent oxygen shall be used by all
crewmembers for takeoff and landing.
The most important physiological measure at any altitude is the alveolar partial pressure of
oxygen since this determines arterial oxygen saturation and thus tissue oxygenation. For
practical puiposes, any altitude may be expressed in terms erf P02(alv) while breathing air or
while breathing 100 percent oxygen. For establishing limit altitudes, this P02(alv) is the
deciding factor.
Respiratory Adjustments to Altitude
The critical P02(alv) at which the average individual loses consciousness on short exposure
to altitude is 30 mm Hg. This corresponds to 23,000 to 25,000 feet on curve A of Figure 1-4. In
the complete aBsenee of respiratory adjustments to altitude, the same P02(alv) would be
encountered at about 1 7,000 feet.
Applying similar considerations to 100 percent oxygen breathing altitudes, it is evident that
hypoxia-induced hyperventilation, as reflected in the course of the PC02(alv) on curve D of
Figure 1-4, does improve the P02(alv) measurably. Thus, the 30 mm Hg P02(alv) in this case is
at 47,000 feet (curve C) willi respiratory adjustment and 44,000 feet without it.
Comparisons can be made between different barom|*tiac pressures wfalGk produce ihesame
alveolar PO2 when breathing air in one case and 100 percent oxygen m the other, in order to
establish "physiologically equivalent altitudes." Actually, physiological states cannot be
compared solely on the basis of P02(alv) but must consider PC02(alv) and ventilation also,
ance a change in one will cause change in the others until a steady state is reached.
The time necessary to reach a steady state at variouis altitudes is given in ,Fi^re 1-5. Note^
that even at the relatively low altitude of 18,000 feet, a steady state is reached only after an
hour of respiratory adjustment. For practical purposes, the P02(alv) may be used without
considering respiratory adjustment in establishing physiologically equivalent altitudes.
Ten thousand feet during daylight is specified as the Umit abqv* which, in nonpressurized
aircraft, crewmemiers must use oxygen. The P02(aly) at 10,000 feet, breathing air, is
122
Physi'ology* of Flight
approximately 61 mm Hg, wMieh produces the maximum acceptable degree hypoxia whii^
Navy and Marine Corps aircrewmen are allowed to undergo. As a consequence, all oxygen
equipment and barometric controls are designed to maintain the user at this physiological
equivalent or betoW.
BAROMETRIC PRESSURE mmHg
500 400 300 200
!0 IS 20 25 30 35 40 50
PRESSURE ALTtTUOE - 100© ft,
Figure 1-4, The partial pressures of respiratory gases when breathing air (A, oxy-
gen; B, carbon dioxide) and using oxygen equipment (C, oxygen; D, carbon'
dioxide). The interrupted lines represent the iJieoretic^ cotars^ in file absent^ df
the respiratory response to hypoxia at altitude (Boothby, lovelace, Benson, &
Strehler, 1954).
Having arrived at the allowable lower limit of P02(alv), various equivalent altitudes yielding
the same P02(alv) can be compared. In breathing oxygen not under pressure, Table 1-10 shows
a P02{alv) of 61 mm Hg at 39,500 feet^ which is, therefore, the upper hmit for flying without
positive pressure breathing. Similarly, other limiting altitudes ate noted.
1-23
U.S. Naval Eli^t StaiigeoaL's Manual
0.70 ' ' 1 1 1 I I I
G.L. 0 10 20 30 40 50 60
MINUTES AT ALTITUDE
Figure 1-5. The respiratory exchange ratio in the course of exposures to 10,000,
15,000, 18,000 and 25,000 feet, indicating the duration of the "unsteady state"
(Bootfaiby, Lorelaee, Benson, & Strehler, 1954).
A question may arise as to why 10,000 feet while breathing air, or a P02(alv) of about
60 mm Hg,,Was selected as the tipper hmit for flight without oxygen. Reference to Table 1-6
shows that 10,000 feet is the upper limit for the irwiifferettt ttiife of hypoxia. Even more
important, reference to the oxyhepo^obin saturation curve shows that ascent to 10,000 feet
causes a decrease of only about seven percent in the oxyhemoglobin saturation, since at
10,000 feet the hemoglobin is still 90 percent saturated. However, rather small increases in
altitude thereafter cause a rather marked steepening of the slope of the curve. Certainly a
2,000 to 3^000^ foot difference would mt matter tnu@h, but anything over that becomes
unacceptable; hence, the NATOPS limitation to 13,000 feet for not over three hours for certain
types of flights.
The theoretical considerations just discussed set limits which are useful in making
predictions and calculations. In raUitary operations, however, many variable factors must be
taken into account. If the oxygen mask suspension is not tidily tdjitlMed, or if the mask is
Physiologjr of Flight
improperly fitted to the aviator, a lower P02(alv) will be measured in the individual than would
he predicted using that equipment, due to dilution of the inspired oxygen with cabin air. There
are other factors which could also account for considerable variation in the absolute PO2
deUyjiFfttL to 0m ftrjiphesijft tb* ^me^tittt^e using the same equipjoiettt $t\tb^j|ame setting, but
on different days or even different flights. '
Table 1-10
Limiting Altitudes for Respiratory Functioning
Altitude
Atmos-
pheric
pressure
Onm Hg)
Alveolar P03 (min Hg)
Breathing
air
Breathing
100
percent
Re?ctioa
Protection
63,000
50,000.
4},ooo,
39.500-
35,000.
33.70O-
Z7,ooo.
18,500.
10,000.
5,000.
Sea level..
47
By
144
179
371-
53-3
632.
760
37
61
79
103
44
61
90
103
iSo
300
443
55°
673
In theory, body water
vaporizes at this
altitude or above.
Effective limit for short-
time mask pressure
breathing..
EffecdVe finiit'oif pftii-
sustained flight.
Ojtalv) drops to level
equal to 10,000 feet
even with 100 per-
cent O2.
02(»iv) with 100 per-
cent O2 equal to that
at sea level breathing
air.
Usual lowti' limit for
possible oc^nctice^of
dysbarisra.
Lower limit for com-
pensatory stage of
hypoxia.
Lower limit for hypoxic
effects on special-
Full pressure suit man-
datory for any
higher altitude.
Full pressure suit man-
datory for, e^ftcnded
exposure above
this altitude.
Limit for oonpressutc
breathing nasl^s.
Majdmum altitude main-
tatefl*6y'fulf^C55ute
suit. -..
Regulators begin pos-
itive pressure Oj
delivery.
Diluter demand Oa " "'
system goes to loo
percent Qa-
O2 used on all flights
above 10,000 feet.
O2 is recommended
above 5,000 on
night flights- I
(VS. Naval Fiyit Swgeon'i Manual, 1968).
1-25
U.S. Nwal F&{^t 8111^11% Manual
Individual variations in d^rion rates for tiie alveolar membrane, or in the amount,
circulating hemoglobin, or in several other physiological variables, could also result in a lower
arterial PO2 than expected from the same P02(alv). The significance is that the range of
vatiailffity'' Bol* in tojipfy teiS imong individtt^ig ittust ISe iiompensated for bfthfe supply of
oxygen. The mechanical means will be discussed later, but one exiilnfild of tiie built-in safety
factors in oxygen equipment is given here;
From calculations of P02(alv) as noted in Table 1-10, 33,700 feet is the altitude at which an
individual breathing 100 percent oxygen has the same P02(alv) as an individual breathing air at
sea level. If no safety factor were included, llic anrntid of the dituter-demand oxygen regulator
would be set so tiiat the i^^olator would deliver lOOf^rcent oxygen at that altitude. Oxygen
would be wasted if the regulator were set to deliver 100 percent at any lower altitude. (The
reason for attempting to conserve oxygen is that oxygen <|uantity, like fuel quantity, is a
limiting factor on aircraft range.)
In actuahty, the aneroid on the d^tt^et-demand regjuktor is set to deliver 100 percent
oxygen at 27,000 feelr rather than at SS^fOO. SnA safety factors are built into almost all Navy
life-support equipment, not only to anticipa^ the wide variation in human response, but also to
guard against some slight misuse or maladjustment of the Equipment.
The theoretical upper limit of altitude which can be endured by the unprotected body is the
point at which the ambient pressure is equal to or lower than the vapor pressure of water at a
body temperature of 98.6° F. Above tiiaf Umit, much of the water in the body would vaporize.
Theoretically, this would occur at 63,000 feet with a barometric pressure of 47 mm Hg.
Actually this "critical" altitude must be modified upward since the water in the body is
contained in the pressure vessels of cells, intravascular spaces, etc. The only situation in which
the body water might vaporize is one in which an aviator is flying at or above this Umit altitude
(with the cabin pressurized to a much lower altitude) and experiences a rapid decompression to
ambient pressure.
This upper Hmit has been tested experimentally and appears to be rather on the low side of
the actual figure.
In experimrats on the unprotected hiKtttatt hMid (F^pire 1-6), it was found that a pressure
below that equal water vapor pressure at skin temperature was required to cause vaporization
of body water. The discrepancy may have been due to the forces exerted by connective tissues
within the hand and the elastic nature of the skin covering.
1-26
zoo
100
E
E
I 50
111
§40
«
30
o.
o
p 20
UJ
z
o
K
10
o
??
9
0 _
-
-
-
o
0
i ■ . . :
-
N
VAPOR PRESSURE
OF WATER AT SO-F
—
■ /
NO SWELLING 0^
THIS EXPOSURE
t- — ~
1
i
,1
3S^
40,000
45,000
SOjDOO
1-
60,000 li-
UJ
a
70,000 p
<
H
Z
80,000 liJ
I
SOjOQO g
lOOpOO
llOiC^O
0 2 , . * , ' ® , ^ I'' . .
EXPOSURE TIME BEFORE SWELUN6-MIN
ISgilie 1-6. Water vapor in tissue at extreme altitudes '
. . . (Bi|llli«8, &:Rpth, 1$^), , ; ,
Appearance of water vapor occurred suddenly and.lQ^ifested itself by marked swelling of
the hand after a variable time at altitude. After appearance of swelling, the pressure in the
altitude chamber was quickly raised; the hand was examined periodically. The upper point (o)
represents the first point at which swelling was no longer visible to the eye.
If chamber pressure was again lowered slightly, swelling again appeared, indicating/^
continued presence of bubble nuclei in the hand tissues. This suggests that once water vapor
bubbles appear, oxygen and carbon dioxide diffti^into the bubbles, which beQaittf -^wsfotjo^fj^
into bubbles of gas saturated with water vapor. . , ' .
For the Navy and Marine Corps aviator* iie NATOPS M«nuali OP^fAVINST 3710,7 series
Hmits flights in pressurized aircraft flown by aviators not utilizing fuU pressure suits to
50,000 feet, .,
1-27
U.S. Nav4 ni#it SuEgeon'B Manual
Positive-Pressure Breathing
When breathing 100 percent oxygen in an unpressurized aircraft, the Hmit of P02(alv) of
about 60 mm Hg is reached at 39,000 feet. Since military aviation exists to win battles, and
since, even in today's air warfare, an altitude advantage may be decisive, some means must be
found to extend, the limits of tbe aviator's physiological ceiling. The only way in which this can
he done is to apply positive pressure to the 100 percent oxygen inhaled by fte aviator. In its
simplest form, this is applied by a positive-pressure repilator to a pre^re-breathing mask, thus
increasing the P02{alv) by the amount of the pressure applied in excess of ambient. However,
the increased intra-alveolar pressure also may cause serious side effects which depend upon the
amount of pressure applied.
EMsting's excellent review of the physiology of pressure breathing is available in Gillies'
'PBXtbook of Aviation Physiology (1965a). For present purposes, a short summary will suffice.
To understand the mechanisms of pressure breathing, consider the following example.
At 39,000 feet, breathing 100 percent oxygen, the PO2 is about 64 mm Hg, the Navy's
liiniting pfe^ure. As the ascent continues, i3ie regulator increases the pressure at which the
oxygen is delivered so as to maintain a P02(alv) of about 60 mm Hg. At 43,000 feet, the
regulator is delivering about 15 mm Hg positive pressure. At this altitude, PB is 122 mm Hg,
PH20(alv) is 47 mm Hg, and Table 1-4 shows the PC02(alv) to be about 32 mm Hg. Therefore,
without the positive pressure, the regulator would be delivering 122 minus (47 -1- 32) or
43 mm HgP02(alv). This is equivalent to a 15,000 foot altitude when breathing air. With the
added 15 mm Hg positive pressure, however, the P02(alv) is 43 + 15 or 58 mm Hg, very close to
thelimit pressure.
In view of the side effects, 15 mm Hg represents a practical maximum for sustained positive
pressure. The major effects (due entirely to increased intrapulmonary pressure) are decreased
venous return to the heart with consequent decreased cardiac output, increased arterial blood
pressure, distention of extrathoracic veins, carflia, md possible rupture of alveoli. Alveolar
rti|!|ure has been shown to occur in aniteals at pressures of ^0 mm Hg with an open thorax or at
about 100 mm Hg with a normal chest. The decreased cardiac output plus the tachycardia result
in a marked decrease in stroke volume. Furthermore, Ernsting states that positive pressure
breathing leads to syncope, but the length of time which elapses before onset of syncope
depends primarily on the pressure applied. At a positive pressure of 20 mm Hg, for example,
most subjects can pressure breathe for 30 minutes without syncope.
The advantages of a positive pressure mask are:
1. The equipment is inexpensive, rehable, instantly available, and requires little maintenance.
1-28
Physiology of Fli^t
2. With a small amount of training, a definite increase in service ceiling catt be obtained 1)0^
• iflle aiuerewman, •
The disadvantages are:
1. The service ceiling increase is small (about 5,000 feet) and limited in duration.
2. Physical injury to the aircrewman may occur as a result of pressure breathing.
3. Pressure breathing is opposite to the normal breathing pattern in that inhalation is
ppsiye and exhalation active, thus traming and familiarization in the technique are
required.
4. The process of pressure breathing is fatiguing.
5. Voice communications are difficult during pressure breathing,
6. Hyperventilation with resulting respiratory hypocapnia is common, even in experienced
aviators.
The use of pressure breathmg in ahcraft is almost exclusively reserved for eaaergeneies, such
as would be caused by penetration or disruption of the aircraft pressure cabin. However, the
A- J. 3A mask and att repilators in genetd use provide this modality, and the aviator must be
prepared to use it if necessary.
Bailout Oxygen Supply and Special Breathing Techniques
AH tactical jet aircraft have an emergency oxygen supply in a high pressure (18,000 psi)
oxygen cylinder contained in the rigid seat survival kit of the ejection seat. There is a different
capacity cyhndet for each type seat-aircraft combination, so that oxygen durations for a given
flow rate cannot be calculated. The range of capacities is from about 47 cubic inches in the A-4
to about 103 cubic inches in the F4 ah'Cfaft.
A current requirement for emergency oxygen systems states that the capacity must be
sufficient to provide oxygen to an aviator following an ejection at 60,000 feet for the entire
duration of descent, plus an additiond five «iinutes at sea le'rel. The iunount required would be
about 120 cubic rnchm vritii pt$$mt regulator.
The emergency oxygen supply is automatically actuated during the ejection sequence and
provides oxygen through the minireg and A-13A mask during descent.
nme to Ground. An emergency oxygen supply is necessary for use during the time requu-ed
for descent by firee fall from high altitudes, op the even longer times when the psra^ute is
opened prematurely. Table 1-11 shows that from 40,000 feet, time of useful consciousness is
1-29
U.S. Naval Flight Suregon's Manual
18 aB@iiail#j wiille tiwi' to fri© fall to 14,0jM feet; is 90 seconds, and time to descend to
14,000 feet is 900 seconds (or 15 minutes), with the 28- to 30 foot parachute open. Obviously,
some provision must be made to keep the pilot alive during such a parachute descent.
Barometrically actuated parachute openers allow an aviator to free fall in the unconscious
condition and survive, but accidental parachute deployment at high altitude would cause certain
death or at least uncotisciouaiess from hypoxia if emergency oxygen could iiot be supplied.
Note that in Figure 1-7 the time to free fall from 28,000 feet to 14,000 feet is &e same as the
useful consciousness time at 28,000 feet. For rough approximations, therefore, 28,000 feet is
the highest altitude from which free fall can be accomplished while breathing ambient air and
retaining consciousness. Actually, the lime of useful consciousness increases as the subject falls,
but this may be considered a safety factor.
Table 1-11
Period of Useful Consciousness in High Altitude Bailout
Bailout altitude (feet)
(Time
in seconds)
Usefal
conscious-
ness
Frec'faU
to 14,000
(feet)
zS- to 3o-ibot chute to 14,000
feet
7S.«»
11
150
i,68d C18 minutes).
55.00°
11
lie;
i.ioQ (lo minutes}.
i8
90
About 500 (15 minutes)-
75
€0
€00 (lO miautes).
(U.S. Naval Flight Surgeon's Manual, 1968).
Emergency Breathing Techniques. In earlier times, several techniques were developed for
increasing the pressure of oxygen in the aiveoU by alteration of breathing. These are
1. hyperventilation
2. "grunt-breathing," where a deep breath is taken, the glottis is closed, a hard grunt is
made, then the breath is released. The entire process is repeated as often as necessary.
3. "peak-breathing," where a deep breath is taken and released while repeatedly shouting
the word "PEAK" with short, rapid exhalation e^ort, again repeating as often as
necessary.
Such methods of pressure breathing may in theory give sufficient P02(alv) increase to allow
retention of consciousness during free fall from high altitudes. Generally speaking, such
methods ate ho longer necessary or practiced due to ad^yption of the mmiature oxygen
tegulator, which allows regulated breathing of emergency bXj^eh diiriiig descent.
130
Physiology of Eli^t
SEA LEVEL
Fi^ire 1-7. Descent to safe breathing altitude
(Carlyle, 1963).
Acclimatization
Acclimatization to altitude is primarily of importance for aviators suddenly required to
begin day-to-day ground operations at altitudes in excess of 15,000 feet. Definitive work on
establishing the exact chronology of the biochemical and physiological mechanisms remains to
be done. The most accurate measure of complete acelimatization is an appropriate increase in
hemo^obin in the blood and a heart rate which is equal to or less than that at sea level, both at
rest and with exercise.
Considerable research has been conducted concerning acclimatization effects on the
Peruvian Indians of Morococha, who spend their entire lives at altitudes above 10,000 feet.
They apparently have adjusted completely to the low ambient pressure and even engage in
strenuous physical actMtjr with no lU effects. That this accUmatization is genuine is shown by
the fact that tiiese individuals demonstrate a much greater duration useful consciousness time
when exposed suddenly to great simulated heights in an altitude chamber. For example, during
a test at 30,000 feet, half of the exposed natives retained fuU consciousness and were able to
write for an indefinite period of time (Velasquez, 1959).
1-31
U.S. Naval Flight Suigeonls Manual
One of the principal adaptive mechanisms of natural acclimatization is a lessening of the
PO2 gradient from inspired air to mixed venous blood as shown in Figure 1-8. It is apparent
that, fiat Moroeddhm te^4m% mechanisms for the trantfet of oxygen within the body have
d^vdoped to a remarkable di^reeof eli&ieii&y*
(mm Hg)
140 -
120 -
100 -
80 -
60 -
40 -
20 -
oL
TRACHEAL
Alt
AIR "
' AtlTiERIAL
MEAN
CAPILLARY
BLOOD
MIXED
VENOSJS
BLOOD
LIM&
\
MOROCOCHA
° □
MEAN i S.E
(mmHg)
TOTAL
DROP
LIMA
l47.StO.09
50
96.210.55 j 87.3±l.5e |
8 8.9 30"
572±0.46 1 42.1 ±053
1 15. 1
104.9
e3.4i0.09 1 46.7±0.36 | 45.240.72 |^^^^M5*0.52 j 34^±0.54
36.7 1.5 6.9 3.5
4a .6
Figure 1-8. Mean PO2 pressure gradients item tracheal ai" " - " .ed veftoUB blood
in native residents of Lima (sea level) and Moi jcouiia (4,540 m). Mean values
correspond to two groups of eight healthy adult subjects each, studied at sea level
and at high altitudes. Alveolar air, arterial blood, and mixed venous blood (from the
pulmonary artery) obtained simultaneously, at rest in the recutnbent position.
Mean capillary blood PO^ calculated (Hurtado, 1964).
Another change noted in high altitude acclimatization is an increase in pulmonary
ventilation. & iKe libromdia residjent?, the ventflation was found to be about 20 percent
gi<eafer than in othet jp^ojtfe at sea level, this percentage rises to about 40 percent if related
tti body weight or to body surface area,
1-32
Physiology of Flight
Although cardiac output is Uttle changed in the acchmatized individual, there are a number
of other changes related to the vascular system. It has been demonstrated repeatedly (Hultgren
& Grover, 1968) that prolonged or permaneait exposure to high altitude prodwces poiycy&emife.
Eesidents of Moroeocha, for example, were found to have * agraieant incrfafiem the number
of red blood cells and amount of hemoglobin and in the hematocrit, but normal sea-level values
for leucocytes and platelets. These last characteristics confirm that a hypoxic condition
constitutes, so far as blood is concerned, a specific stimulus for erythropoiesis only.
Additionally, it was found that there was an increased vascularization within the bodies of
animals living at the high altitudes, Hiere was a significant increase in number of capillaries
within any section of tissue. Although such quantitative determinations have not been mad© in
humans, indirect observat^ns seem to indicate that a similar condition exists. The increased
oapillary bed is an important adaptive mechanism inasmuch as it ^eatly favors the diffusion of
oxygen from blood to tissues. •
Van Liere and Stickney (1963) summarize several studies of possible acelmaatization made
by aviators. In generd, these studies show minimal change, if any. In one study, some eradence
was found of heightened erythropoiesis, but the authors concluded that on the whole there was
no evidence that aviators developed compensatory adjustments to a constant and significant
degree. Inasmuch as alveolar oxygen tensions for aviators are maintained through the use of
oxygen equipment at levels equivalent to 10,000 feet or less, the appearance of major
accUmatization effects would be rather surprising.
Hyperventilation
Hyperventilation is defined as an increase in depth and/or frequency of breathing. The cause
for the increase may be physiological, as in the case of increased arterial (art) PCO2 due to
breath holding, or it may be "voluntary" or "active," as in the case of the experimental subject
who is asked to hyperventdate. Another "voluntary" cause is mxiety or fear^ although the
individualis usually unaware that he is hyperventilating.
The physiological stimuh for hyperventilation are blood carbon dioxide buildup, or to a far
lesser extent, blood oxygen decrease. In gradual ascent to altitude without supplemental
oxygen, significant hyperventilation due to decreased P02(art) occurs very gradually, if at all.
However, voluntary or anxiety-induBed byperventilation can, and. frequently does, occur at sea
level, but may occur under any set of circumstances.
The net result of hyperventilation, regardless of cause, is hypocapnia with varying effects on
blood oxygenation. The hypocapnia may be of such severity that tetany may oeeur. If tbe caUffc
is hypoxia, a mixture^of symptoms due to hypoxia and fliose diie to hyperventilation m^ be
present. The differentiation of symptoms due to each cause is difficult.
1-33
U.S. Na?al Fli^t ^urgeon'B Manual
The hyperventilation syndrome can occur in the presence of normal P02(alv) and is
common in the general population as well as in aviation personnel, both in the air and on the
ground. It is usually associated with raixiety or excitement and frequently occurs in response to
em^en^ 'situations. Conveteiiy^'lfcfe43f»peiTfaft#ati« #^ may precipitate an emergency
wh«a it aevfelopsiitf an aviato* W or in an altitude ©h^Bar firing indoctrination training.
Typical symptoms of hyperventilation are a feeling of apprehension, dizziness, and weakness,
numbness of the face, fingers and toes, neuromuscular irritabiUty with fasciculation and tetany,
Hiett^' fidltfusiirtHfitf a severe nature, and possible syncope. The most prominent sign is increased
respiratory rate and/or deptl?^.
Since many of the same symptoms occur with hypoxia, how can one make an immediate
differential diagnosis? Such an undertaking is difficult because of the interdependent nature of
the two conditions. But, if it is known that oxygen is being supplied, and that the major
complaints are numbness and tingling of the hands^ face, and feet, then hyperventilation may be
postulated^
All aviators should be familiar with the symptoms of the hyperventilation syndrome, and
they should be trained to take the necessary corrective action. Particularly, pilots must be
warned not to disconnect the oxygen supply when hypoxia or hyperventilation is suspected.
HyperventUation Effects on Oxygen Levels. The effect of respiratory compensatory
mechanisms on P02(aly) during expoaire to decreased oxygen partial pressures is shown in
Figure 1-4. The meehanisnis*aie^0iH©what eomplex. . •
Hypoxia causes hyperventilation when the P02(alv) drops to a sufficiently low level. This
results in hypocapnia iait matter of secoiids as carbon dioxiie is Mown off, which in turn causes
an increase in blood pH, as noted in Table 1-12. It also results in an increased ^©^(art^y JiHlt the
alkalosis as well as the decreased PC02(art) shifts the oxyhemoglobin dissociation curve to the
left (Bohr effect), as noted in Figure 1-2, causing relatively less 03||f gew to hi liiftde availal^^ to
the tissues. ' -
The alkalosis also firoduces cerebral arterial vasocottBtaietioli. Itt a sli^f conducted at
39,000 feet, as shown in Table 1-13, hyperventilafion while breathing lOO'percent oxygen
increased P02(art) markedly, but the resulting hypocapnia decreased cerebral blood flow by
almost 50 percent. This resulted in a net decrease in brain oxygenation when compared to
normal breathing of 100 percent oxygen at normal rate and depth at that altitude. On the other
hand, when breathing normally at the same altitude on a 30 percent carbon
1*34
Physiology of FU^t
dioxide - 70 percent oxygen mixture, brain oxygenation increased slightly over normal
breathing of 100 percent oxygen despite lower P02(art) values, because the increased PC02(aFt)
caused cerebral vasodilation which restored cerebral blood flow to aea-level vdues. This effect is
limited, however, to altitudes between 35,000 and 40,000 feet.
Table 142
Effect of N<Wni8l Inereased and Decreased Alveolar Ventilation
■ ' =' ' • on Arterial Blood
Type of ventilation
(Resting man)
Alveolar
ventilation,
L/min
Aheolttr and itterial
gas tensicdt*
gas contents
Arterial
pH unita
04
nun \ig
COj
niin
Oj
percent
saturated
CO,
mM/L
1.50
67
88.;
17.1
7.34
4»-7
104
97-4
11. 3
7,40
Hyperrentiliinoa. . ,
7.50
113.
1-3
98.8
17- S
7.56
%«idi case, lespiratory exdta^ni&t irf fli j md O2 conaumption of 250 ml/min are assumed,
and the volueg an eiiteidated from tiie CO2-O2 diiignBi of lUJin and Fenii (Bryan, 1964).
Table 1-13
Effect of Hyperventilation on Respu-atoty Presssures
rt a Simulated Altitude of 39,000 Feet* Breathing 100 Percent
Arterial Po;
Arterial Pcoj
Arterial hemoglobin saturation
Mean brain capillary Poj. ...
Cerebral venous Pbj
Cerebral venous hemoglobin sanif aticm .
Respiration rate
Normal respiration
39,000 Ket
55inm Hg. . .
40-3
87.1 percent.
39'3
^
percent.
xi.4/lninute .
Hyperventilation
39,000 feet
Sinun Hg,
11.7.
9£.9 percent.
jj.i.
10.
37.7 percoit.
33.g/niinote,
(U.S,Navd Flight SmgeonVMmal, ma). '
Oxygen Paradox . >
The restoration of normal alveolar oxygen tenfflon in an hypoxie aubject can be
accompanied by a tempotwy ittcreaee in severity of the symptoms. This condition is referred to
1-35
U.S. Naval FK^t Sui^oA'b Manual
as the "oxygen paradox" and is generally found to occur with sudden oxygen administration
and reoxygenation. Spasms and unconsciousness can occiu- during the episode, which in=ay last
from a few seconds to several minutes. '
The hypocapnia accompanying hypoxia, as well as the fall in arterial blood pressure, may
work in concert to cause a reduction of cerebral blood flow following reoxygenation of the
blood. This reduced blood flow would serve to intensify the cerebral hypoxia for a brief period
while the carbon dioxide tension of the brain tissue returns to its normal level.
In other cases, respiration is markedly depressed by administering oxygen when a patient
has been hypoxie for some time. The hyperventilation associated yMi % hypoxia, when
combined with the decreased supply of tissue oxygen, causes hypocapm% of such a degree that
the carbon dioxide stimulus to respiration is removed. In this case, the hypoxic stimulus is the
only one which remains, and it is removed when pure oxygen is supplied, causing sudden onset
of apnea, with gradual return to normal respiration only when the carbon dioxide level
increases.
In still other cases, Luft (1965) found that sudden exposure of an individual at 33,000 feet
on 100 percent oxygen to ambient PO2 at altitudes above 52,000 feet caused almost instant
hypoxia. Oxygen saturation dropped rapidly, reaching a minimum in nine to ten seconds. At
exactly 16 seconds unconsciousness set in abruptly. In succeeding tests, the time of exposure
was successively reduced from 16 to 12 to 8 seconds in order to determine the minimal
exposure neee^ary 4o emm Mm&mmomnm. The subjects became unconscious in all tests in
which they were exposed for over six seconds, but unconsciousness re|ula3rly occurred only
after 15 to 16 seconds, despite the fact that the subject was again breathing 100 percent oxygen
by that time. This delayed action of hypoxia was absent only when exposure to the hypoxic
stimulus was ilefe>4han six seconds. Luft postulates that the latency of the hypoxic symptoms
cannot be atttbuted to lungirain circulation timeldone, but must also involve aerobic or
anerobic reserves in ffie'eerebral tissues.
Oxygen Toxicity
fissures Greater Titan One Atmiokphere. Oxygen is toxic to all mammalian biological
systems at partial pressures greater than 760 mm Hg. In general, the greater the partial pressure
of oxygen, the shorter is the time before toxic manifestations occur. The toxic effects are
produced at a cellular level and are manifested primarily in the central nervous system and the
pulmonary system. In humans, central nervous system signs and symptoms occur within
fflinotes as «jfartial pressure^of oxygen equivdeut^to 10©-lfeiet of water. Facial muscle twitching,
nausea, dizziness, anxiety, conftisiDn, and incootrdination may occur before the onset of grand
1-36
Physiology of Flight
mal siezures. If the oxygen partial pressure is not decreased after the onset of the convulsion,
status epUcpticus will occur, followed by death. ' -.cih
Usually, consciousness is lost at the onset of the convulsions, and apnea occurs during the
event. The convulsion may last for one or two minutes and, in the submerged Individual,
drowning may occur as a result. Breathing usually resumes spontaneously after the convulsion as
the PO2 is decreased or restored to normal, but the patient remains unconscious for several
more minutes. A period of 30 to 60 minutes of semiconsciousness itti^ iittlttM ldljh ^fe
behavior, great restlessness, tod intermittent sleep.
Exposure to moderately inQceased pW^al pressures of oxygen, i.e., 760 to 1,200 mm Hg,
will produce signs of pulmonary irritation, pulmonary edema, and death, but only after
prolonged exposure of from one to four days. The pulmonary effects of oxygen toxicity thus
are not of primary significance in an aviation survival situation. 1
The phydologieal mechanism for "oxygen poisoning" is poody understood. HQ^s»(Fever, it is
known that at oxygen partial pressures above one atmosphere, so much oxygen is carried in
solution in the blood that the tissues have a higher oxygen concentration and less oxygen is
removed from the hemoglobin. A hypercapnia results which causes cerebral vasodilation with
increased blood flow to, and thus increased oxygenation of, the brain. It^fe lfelieVed likely that
the oxygen has a direct effeet on enzyme systems in the brain. The convulsions result from tfc^e
enzyme disturbance.
The postulated sequence of events leading, to the climcal symptoms of oxygen toxicity
based upon work with animals is as follows:
1. Formulation of lipid peroxides in the brain with tocopherol inhibiting the reaction
(tocopherol-deficient mice are more severely affected)
2 The formed lipid peroxides then inhibit acetylcholinesterase in the 'bram.
Treatment consists of restoring a normal alveolar PO2. Then the convulsion should not
prove fatal. . . ■
Pressures of One Atmosphere or Less. Effects at these piessures ate essentially pulm«atary
and cai^t of atelectasis, pulmonary edema, and pneumonitis in experimental animals. In man,
similar effects have been observed, but again there is a time factor. Comroe (1965) noted that
when 100 percent oxygen is breathed at one atmosphere (760 mm Hg), substernal distress
appears after 12 to 16 hours. It is believed that these effects are due to the direct toxic action of
the oxygen on the lung and may possibly be due to the effect on alwoljd' surfactant.
1-37
U.S. Naval Fli^t Surgeon's Manual
, Pulmonary surfactant is thought to stabilize the alveoH and protect them against an inherent
tendency for collapse (atelectasis). It is also thought to protect the alveoli from puhnonary
edema and hemorrhage and has been found to be missing in cases of "oxygen poisoning."
Acceleration Atelectasis. The last oxygen effect which to^f be lOoSely grouped under flie
general heading of toxicity is atelectasis occurring while breathing 100 percent oxygen under
acceleration, although the term "oxygen toxicity" in this context is a misnomer. Acceleration
^tdfeCtefe is ineluded in this section only because it occurs when an aviator is breathing
100 percent oxygen. Repeated acceleration-producing maneuvers in flight cause a marked
reduction in vital capacity, along with x-ray demonstrable basilar atelectasis when 100 percent
oxygen is breathed. When a 50 percent oxygen/50 percent nitWgen mixtflre is breathed, 0% a
minimal reduction of vital capacity and minimal radiological signs of collapse are founC
As noted by Emsting (1964), the primary factor responsible for the atelectasis is probably
the complete cessation of basUar alveolar ventilation under acceleration. There is also markedly
increased blood flow to the basilar alveoli as opposed to the apical cjnes, along with a reduction
in basUar alveolar volumes as the weight of the lung under accetoaftion compresses fte l^g^
against the diaphragm. With these three factors acting in concert, and when the alveoli in
question contain only oxygen, water vapor, and carbon dioxide, oxygen absorption (the main
cause of acceleration ateleo^) leads to alveolar coUapse, and atelectasis can occur very
rabidly.
If nitrogen is present in the inspired gas, however, the gas absorption and consequent
alveolar coUapse are greatly slowed. Ernsting states that the time required for complete
absorption of gas contained in the lower quarter of the unventilated lung (with normal blood
flow distribution) is increased from five minutes on 100 percent oxygen to about 25 minutes on
50 percent oxygen/50 percent nitrogen. In ad^tion, there is evidence that nitrogen in tiie hing
acts as a "sprii^" by preventing alveolar collapse when aU the oxygen is abscM'bed.
Pulmonary atelectasis during flight may result in several performance-degrading effects,
mcluding distracting or perhaps even incapacitating cough and chest pain and arterial hypoxia
due to the shunt of venous blood throu^ the nonaerated alveoh.
'Till'
Ernsting and others have suggested the U8s of a nitrogehi^oxygeh mixtilre Ife^^vent
atelectasis. The experience of the Navy has been that atelectasis, although it occurs, is not a
problem because the accelerations required to produce it would occur only during air combat
maneui^ering and are hmited in duration to several minutes. In earlier aircraft using the
diluter-demand oxygen regulator, acceleration atelectasis was not a problem at low altitudes
1-38
Physiology of Eliglit
because the oxygen was diluted with air. New aircraft using Uquid oxygen converters and
miniature oxygen regulators do not dilute tlie oxygen with air, even at low altitude, so that
conceivably aceeleration atelectasis could be a hazard on any missioii requiring high-G
maneuvers. The Flight Surgeon should remain aware that coughing, substernal pain, and
decreased altitude tolerance may indicate the development of this condition. Tn any event,
acceleration atelectasis usually resolves itself in a few days with Uttle or no treatment.
Cabin Pressurization
Any time a pressure cabin is being utilized, there is danger of rapid decompression due to
equipment failure, structural fmkm, or human error. In this situation, the transition from #ie
quiet ease of pressurized high-speed flight to a hostile environment is quite rapid. If equipment
f aUs or if training has been inadequate, the man, the aircraft, or both may be lost.
All military fighter and attack aircraft have two systems for insuring a proper supply of
oxygen. One is fee pressure cabin, for which a pressure profile is shown in Figure 1-9, and the
other is the liquid oxygen converter, regulator, and mask system. In peacetime operations, the
two systems used together provide a good working environment and exc(i]letil safety. In a
combat situation, however, any hole in the pressure cabin from a missile near-miss, hostile fire,
or blown canopy would necessitate descent to and maintenance at or below 25,000 feet. Any
( V defect in the cabin pressurization system would have the same effect.
Hypoxia Rceyeiition
Mamtenance and In^ecaon. All jet fighter and attack aircraft require use of oxygen masks
duritig the entire flight. To iMUre that the oxygen iystem perf onus its function, pilot training
must include study of the system and preventive maintenance measures. Pilots must understand
the functioning of oxygen equipment, and they must be convinced that under no circumstances
should a leaking mask be used.
Scrupulous cleanliness of the oxygen mask must be maintained. It is recommended that
masks be cleaned every week if in constant use, and once a month, even if not used at all.
A thorough prefUght inspection should be made of the dxygen mask prior to each flight.
This should include at least a check of the general condition of the mask and its connection and
a check to see that both inhalation and exhalation valves are properly seated and hose
connections are adequate. The plot should be certain that he can inhale and exhale normally
through the mask prior to manning his aircraft.
Finally, a thorough preflight inspection should be made of the aircraft oxygen system.
1-39
U.S. Nav^^ Plj^J; §ur^on's Manual
m
o
o
o
]
1 1 I
Q
s
1
\
1 1 1 1 1
V
mr
mr
TTrrj
TTrr|
] 1 M
TTTT
1 1 N
TTTT
1 1 1 r
Mil
1 ri 1
TTTT
TTn-[
1 1 n
TTTT
TTTTf
TTTT
TTTT
MM
■mr
■mr
TTTT
15
20
25
30
35
40
45
50
55
AIRCRAFT ALTITUDE - 1000 FEET
Figure 1-9. F-14A aircraft caiiin preaaure schedule.
Emergency Procedures. Standard emergency procedures be foUowed in the event of
suspected hypoxia are: Immediately select 100 percent oxygen if using a diluter-demand
regulator, and immediately descend to 10,000 feet or below. (This is the altitude at which to
<3h^lc for posaibl© malfunctioning of the equipment. Such checks should not be performed at
the altitude at which hypoxia is first subjected.)
Hypoxia Detection by OrAem' MUtary air controllers and tower operationB^^^ionnel, as
well as other aviators, should report to the FUght Surgeon, as an emergency, any incidents of
incoherent or seemingly intoxicated speech which they detect in air-to-ground or air-to-air
communications. This may he the only evidence of hypoxia and occasionally some assistance
can be given iie aviator by radio.
Aviators should be encouraged to report every instance of severe headache or period of
extended lethargy following a high-altitude flight. Such incidents caU attention to ft,po^le
attack of hypoxia and possible equipment malfunctions of which the pilot may be completely
1-40
Physiology of Tli^t
unaware. The necessity of reporting all cases of known or suspected kypoxia should be stressed
to all pilots, even though recovery is apparently immediate and complete. Remember, there are
no chemical tests, physical evidence, or any other findings to confirm a case of hypoxia once
the flight is over and the aviator is avdlable for examination on the ground.
investigation of Suspected Hypoxic fncidents, The Flight Sargeoh should itieet'the aviator
when he lands his aircraft after a siispectedliypoxio inddent. If the FUght Surgeon knows the
aviators in his unit, he may well note subtle evidence of some residual confusion following a
hypoxic episode simply by engaging the pilot in coversation. A mental status examination and
neurological exammation should be performed as soon as possible, and blood pressure and pulse
rate should be recorded. Then a thorough history should be taken about the suspected iMtiictfeftt;
obtaining as many particulars as possible. These should include
1. symptoms, signs, and reactions during the incident, with the effects of any emergency
measures carefully recorded
2. cabin altitude and duration at this altitude
3. type of mask, ownership, size, and fit
4. type of regulator and regulator control settings
5. duratit>n of fH^t and brief history to include unusual events
6. possible predisposing factors - smoking, hangover, scuba diving, anxiety, carbon
monoxide exposure.
The classic medical procedure of first obtaining a chief complaint, then a history of present
illness, past illness, and review of symptoms, followed by the physical examination, must be
reversed in these investigations. If the history is taken before the neurological and mental status
examinations ate perfomed, the occasional residual defect will be missed.
Condurrefit #ith the physical examination and Mstbry, expeM mitetenatice personnel
should be checking the aircraft oxygen system for normal function, quantity remaining,
contamination, and' regulator control settings, and for evidence of leaks, disconnections, or
faulty gauges.
The FUght Surgeon should have the rested aviator don the oxygen mask and helmet and
should proceed to check the fit of the ma&k on the aviator's face. The mlfek should be eXantiined
bj the Flight Su^on lor eAalation and Midation function and for leaks.
1-41
U.S. Naval Plight Sntgeon^s Maniul
If the entire procedure reveals any evidence of the cause of the hypoxic incident,
responsible squadron line officers should be notified immediately m as,. to pi^Qlude ^iinil^r
incidents, possibly even in aircraft that are then airborne. - , .
Comes offfypoxic Incidents. Mask removal for convenience is one of the most common
causes of in-flight hypoxic incidents. Aviators sonjetinjea remove tfaeir oxygen masks to adjust a
visor or to scratch their face. Because of the insidious nature of hypoxia, such actions are
extremely hazardous. When replacing the mask after only a few moments, an aviator may
become so uncoordinated that he cannot perform the simple motions required and can never get
the mask replaced. He may h^ve guch impairment of judgment fiiat he thinks ^e mask is
p^psgfirly mi^ttftched, when, in fact, it .is not, or he maj tWnk it is no lon^r necessary to reattach
the mask at all.
Should brief removal of the mask from the face be necessary at high altitude, the following
procedure should be followed:
1. Take three or four deep breaths of 100 percent oxygen.
2. Hold breath and remove mask from face.
3. As soon as practicable, replace mask and take three or four deep breaths of 100 percent
oxygen.
Inhdattoii valve problemB in the A-13A osrygen mmk often cause hypotie intaH^nts. The
inlet valves of this ma^ are very sensitive and can easily become inoperative due to a speck of
dust. A small particle which prevents complete closure between the flapper valve mA its seat
will result in a marked increase in the exhalation effort required. The aviator may not realize
that the inhalation valve is almost invariably the cause of an exhalation problem. When the inlet
valve is held open by a particle of dirt, the exhalation pressure exits through it and is then
exertf i on the rear of the exhalation valve, exactly balancing the pressure on the front of the
exhalation valve and preventing it from moving, regardless of the exhalation pressure exerted by
the aviator. When faced with such marked exhalation difficulty in flight, ail aviator could
become so concerned that he would remove his mask in the belief t]j;ia|: lp;hadi,e?:hi|U.ated his
oxygen supply. Indications that he hai- not are the movement of the oxygen flow meter in some
oxygen systems, the oxygen quantity gauge reading in all systems, and the fact that inhalation is
still perfectly normal. Logic rarely triumphs in the face of panic, however, and effectiye training
is the way to minimize such actions.
If exhalation becomes difficult or impossible in flight, the aviator should keep his mask in
place. When exhalation is desired, he should vent the expired air past his chin and out of the
mask. Witli appropriate movement of the mandible and a little training, this is easily
accompMied,
142
Physiology cif lli^t
Exhalation valve problems in the A 13 A oxygen mask also may be the cause of hypoxic
incidents. Functional failure of an exhalation valve is extremely rare. As has been pointed out,
exhalation difficulty is usually due to malfunctions of the inhalation valve. However, the
exhalation rabm Q0-he cause of a dangerous in-flight atiiertlw. The exhalation valve could
be completely uiteateA, aad most oxygen equipnSent tec&nicians would not detect it, nor
would most FUght Surgeons or aviators. The interior of the mask appears to be just as normal
with the exhalation valve completely unseated as with it properly seated. The mask still will pass
tests for function in such a way as to appear satisfactory to most users. The hazard lies in the
fact that when the exhalation valve is in the unseated position, inhalation can permit cockpit air
to enter the mask around the exhalation valve, thus decreasing the oxygen concentration in the
mask. Since lOOipBrcent dxfgen would ipi®i^itejl the mask through the inhalation valves, the
aviator would not tee&me hypoxic at lower flight levels, nor would he detect any difficulty in
exhalation or inhalation. However, when attempting to reach the Hmits of altitude for which the
mask was designed, he would become hypoxic at considerably lower altitudes. This effect is
made worse by any action such as head turning or any maneuver producing acceleration. Such
actions cause some distortion of the Ittlisk and effectively increase iJie leak aperture, in turn
increasing the amount of eb^^t air ilihaled. Again, tike oiilf 'sohtttenttfto this problem is
prevention. Hie aviator must be trained to recognize an unseated exhalation valve instantly
during preflightiiispection (Figure 110).
Another reason for removing the oxygen mask at altitude is the fear of "contaminated
oxygen." Cases of true contamination of the oxygen supply m a cause of hypoxia, illness,
unconsciousness, or any other adverse physiological effect are quite rare. Yet the pilot who
sniffs an unusual odor in flight typically feels his oxygen supply is contaminated and removes
the only source of oxygen he has, usually with dire consequences. While it is true that an aviator
with a sensitive sense of smell may be able to detect "trace" contaminants that are impossible to
exclude completely in the manufacturing process, these are absolutely harmless.
The only answer to the "contaminated oxygen" pro'llfem lies in training, both of the Flight
Surgeon and of aviator. Salient fmsts are: ,",u^m f-
1. For all ptaetical purposes, contaminated oxygen does not exist in the sense that it cairt
cause haJ?mM effects. - I. . -tc -> < i .. • v .
2. %e ^tihdjrdliarin frbtn iuch incidents is hypoxia resulting from mask removal.
3. The procedure to follow if contamination is suspected is to select 100 percent oxygen if
using a diluter- demand regulator. If odor continues or nausea due to the odor ensues,
then descend to 10,000 feet or below, possibly activating emergency oxygen cylinder
en route, and remove the oxygen mask if necessary. '• • ' ■ x t ■
Ir48
U.S. Naval Mght Burgeon's Manual
NORMAL
IF
G
.tJlv; cj> OXYGEN FROM REGULATOR
COCKPIT AIR
EXHALED BREATH
INHALATION VALVE NORMAL
TOHALATION-OPEN
EXHALATION CLOSED
INHALAflON
PAUSE
EXHALATION
MALFUNCTION
EXMAUTION VALVE UNSEATED
1
INHALATION VALVE UNSEATED
In*' ])
L ^
C VALVE BODT 0I31>LACEMENT
D.OIRT UNDER FLAPPERETTE
UNSEATED INHALATION VALVES
) Kgnre 1-10. The A-13A oxygen mask, normal and with maljunctioii
(U.S. Naval Flight Surgeon's Manual, 196S).
Accidental mask detacWent cm. result in hypoxia. Military attack and fighter pilots operate
in a very dynamic environment, performing high-G maneuvers, moving about in cramped
cockpits in order to get comfortable, or jnriaintaining a loo]cQUt for other aircraft, missiles,
birds, etc. Occasionally, a quick-disconnect fitting will separate accidentally, causing an
emergency until it can be reconnected. If the cabin altitude is low, such disconnection may not
become apparent for some time, and the crewmember wiU suffer gradual onset of the early
^niptoms of hypoxia. In cases where the cabin is al aroibient pressure, such symptoms can
nmiMesLiJheiwekes ■faj-'ias short a time saa IB'seieotida (;ei)t^e. 4i>000 feet). To give the
crewmember a chance to reconnect the mask before losing consciousness, the quick disconnect
of the A-13A mask has been fitted with a valve, actuated as soon as the mask is disconnected,
which causes a marked increase in inspiratory effort as a warning. If a miniature regulator is
being used, the warning is that breathing becomes impossible.
I I .Inexperienced personnel collapse more frequently at intermediate altitudes when hypoxic
than do experienced personnel. An individual who is apprehensive concerning a high-altitude
flight may, under a mild attack of hypoxia, hyperventilate to such an extent as to produce a
1*4)4
. Physiology ofrHigit
hypocapnic reaction which can lead to total collapse or to a serious lessening in motor
coordination. In one instance, a passenger on a first jet ride experienced difficulty with his
oxygen equipment, finally turning off the oxygen supply in his struggle to relieve breathing
difficulty. The passengef*iJldiie'tln®>iiiilittS died'in of the pilM's rapid descent ttrid
the immediate availability of medical aid upon landing.
In summary:
1 . Almost all exhalation problems are caused by the inhalation valves.
2, lahala^Qii. |M.ffi(pll|^ if always due to a disconnected hose or exhausted oxygen supply.
3 . When hypoxic incidents oeeiii, loQ^ for unseated exhalation valves.
4, Contaminated oxygm as a cause of hypoxia has rarely been found in the Navy.
5, Training and inspection are the keys to avoidance of hypoxia in aviation.
6. A Flight Surgeon will rarely obtain any positive laboratory or physical findings in a case
of suspected hypoxia, but all such cases should be investigated as thoroughly as humanly
possible.
Provision of Oxygen
Physiologic^ criteria winch should be miet in the provision of oxygen can be stated as
follows: , o
1. The concentration of ©JSygeti deHvefed to the aviator must be adequate to maintain
proper arteriftl o^gen saturatfoft,
2. Gas flow capability j^u^t,,pef(: |to full range of respiratory flow requirements.
3. The resistance to flow st^onld be mnuBiai in order to provide a system which is as
"neutral" as possible.
An oxygen Systems cofl^t of (1) a supply of oxygen, (2) the necessary tubing or hoses to
dietrfibilte the gas, (3) a meanf: of controlling or metering the flow of the gas (regulator), and
(4) a means of directing the oxygen to the respiratory system without inadvertent leakage where
the man is joined to the system.
Oxygen Supply ^simm. 'feere'ate twb t^«a ^ oicygen supply systems euwentl^ in use in
the fleet - cylinders (both low pressure and hi^ presSOre) and liquid oxygen (LOX) converters.
The oxygen cylinders have almost disappeared from use in fighter and attack aircraft, Some
obsolescent training and transport aircraft still use one or the other of these types, and
emergency oxygen cyUnders, often referred to as "walkaround bottles," are another exception.
145
U.S. Naval, fli^t^KifgieonV Manual
The LOX converter is universally utilized in operational jet aircraft because of its advantage
in weight and storage space over a cylinder system. For example, a five-hter LOX converter
weighs 28.6 pounds as opposed to 90 pounds for a high-pressure oxygen cyUnder of the same
eaps^pi^j. stnllffiliEefHires od,y #ll?cttbte feet of space as opposed t# | J ©uM© ?feet for the
high-pressure cyUnder system.
The range of an aircraft with the capabiHty of flying at altitudes requiring oxygen breathing
by the crew is a function of the amount of consumables aboard. These include aircraft fuel,
lubricating oil, drinking water, food, and oxygen supply. The oxygen supply is, in fact, the
hmiting factor on aircraft range sih^e siir-to-aii* f efaelitig hws, ifiMi ii*itec>retieally possible for
combat jet aircraft to pftnaiti &kMm6 until ^sit^ts need ovef&fittliig.
The NATOPS manual for each aircraft contains a table of oxygen duration which is used for
mission planning. Table 1-14, for example, is the oxygen duration chart for the F-4B aircraft.
The chart is based on utilization of 100 percent oxygen at all altitudes and takes into account
evaporation losses which are to be expected from the LOX system. It presumes a value for
ventilation rate somewhat in excess of normal due to possible apprehension or other factors in
the operational situation.
Table 1-14
Oxygen Duration, F-4B Aircraft
Oxygen daration-houfs
Cabin pressure
altitude feet
V,P
Gauge quantity-liters
8
6
4
1
I
Below I
. >;i ill ^
40,000 and Above
60.6
48.5
36.4
14.1
11. 0
6.0
35,000
37.0
ig. 6
11. 1
14. S
7.4
3.6
Duration time is
30,000
1.7. 2.
11.8
t6, 4
10.8
3.4
1.8
Emergency —
halved when two
1.5,000
la. 4
i€. 4
11,4
8.1
4.0
1. 0
Descend to
aew jtnejnbef s are
lO.OOO
16. 0
11. 8
3.6
6.4
1.6
altitude not
using oxygen
15,000
11.8
10, 1
7.6
1.6
1. 1
requiring
10,000
10. 0
8,0
6.0
4.0
1. 0
1. 0
oxygen
8.4
6.6
5,0
1.6
0.8
7-0
5-6
i.S
1.4
0.6
CNAVAIR 01-14SFDB-1, I Oct 1965.)
Liquid oxygen containers are spherical "Thermos" bottles with double-walled vacuum
insulation. Some of the valves used in the liquid oxygen system are manually operated; others
are automatic. The valving controlling the system pressure, for example, is automatically
Physadopf of Hi)#it
aiai(jitt:«d to maintain a system pressure &f Tt^iA iBkn filler valveSf dfl ftg ^ft&r''fea»3i, are
operated manually to allow an initial filling at atmospheric p*^mi*i&. tlttf'is fellowed by a
system pressure buildup which achieves the required 70 psi. An automatic pressure-relief valve
on the converter po^ttv^ly prevents excessive pressure buildup, thus precluding the danger of an
explosion.
If system pressure becomes excessive^ the reUef valve has a cracking pressure of lOO^pgi'ijni
a ftlM^fW* pressHi* of 120 pli. AppJtiMm&ttly litet ©f-l^fd^xyfeh 1\ffl>be lost overboard
durtiig a 24-hour period when the system is not iii use. i ' • '■' ■'■
Tubing for liquid oxygen systems is of aluminum , a lighter material than the copper tubing
used for gaseous oxygen. Because the liquid oxygen operates uiider relatively low pr6i8Sti»e, the
system tubing need not be m strisng as thatused in gaseous oxygen systems-. In th©»LlSX iyitem,
the tubing and its component valves make and msn^n system pressure. When Hquidisxygen is
converted to gaseous oxygen in the tubing of the converter, it expands. When expansion creates
a system pressure of 70 psi, a valve shuts off entry of oxygen from the reservoir into the system.
Excessive gaseous oxygen is carried to an overboard vent through the system's tubing.
Safety Precau^&m in Handling LOX. Oxygen da^ iioiitem, but it suppttets ft^mbustion.
When the percentage composition of oxygen in an atmosphere is raised, the burning rate of
most materials also rises. When 100 percent oxygen is the only component of the atmosphere,
traditional safety measures are no longer adequate to assure safety. The kindling points for
many materials are revised drastically downward.
Any Ky&oCfitisOW^ the form of oil or ^eaife inay loMiiitte with 100 percent oxygen
explosively at room temperature. Any trace of oil or grease anywhere in the oxygen breathing
system may cause a sudden fire, perhaps leading to destruction of the aircraft when LOX or
compressed 100 percent oxygen comes into contact with it.
Since maintenance crews and aviators live and work with LOX and 100 percent oxygen
daily, there may be a gradual tendettiy'tt" relax safety ^^^citfi'csfrt. f*aifflHM^ %ith the
siibstanic^ does not alter its properties. Recently, an experienced aviator returned from a flight
with most of his oxygen mask melted and severe burns over the side of his face caused by his
lighting a match "to get rid of some raveled strap ends." He was known to be a heavy smoker
and had cigarettes and matches in his flight suit. The number of fires resulting from smoking
• wfcile wearing the ox^en i^ijiik wH'ftfever be known, since most such instances l^ave no traces at
the scene of the crash. Sinoking wM© o*yg«ft tf^^ ih use iS Ktrftjly forbidden: by *he
general NATOPS manual, OPNAViNST 3710.7 seri^^s.
147
U.S. Nsi#litt#itf|s^pta's Maniid!
Illiquid Qs^^^^mf^r^^fi^ mmhimA with «tiiiar fiiKbiteii4se§ lueb iaS'%uiiv3iN<^
Lsawdust, cloth, and many others, forms a gel within a very short time. If the mixture is then
subjected to an impact, such as a hammer blow, it will explode with a force roughly equivalent
to a similar weight of TNT. In one example of this most unexpected and little-known quality of
LOX, the technician for a commercial firm supplying LOX to community hospitals had his leg
Mown oi^ itdthout waming or obvious cause. Investigatiou reivealed that tiie event occurred on a
CQM^ete^lfaieed dft^, down the centet <?f?T#i©h ittany veMsIeswer the yeiirs had dripped oil.
When some of thtlLOX being tr^f erred dripped onto the pavement, no notice was taken of itr
However, when the technician stepped on the site of the spillage, a gel of old crankcase
drippings and LOX had formed, and the impact of his footstep was enough to cause the
explosion. ' '
•'• .•>»i'- • ■ ■•.}>t J
It mu^i'lie'ife»<ate|A;aiiK«d:that cloth inqjregnated .i#th LOlC maf j^ve an identicid tea^tion.
If, ia addition, the clothing of a maintenaitee man has been soiled wiArijilj hyibaulic fluid, or
grease, and LOX is spilled on it, tragedy may result. Therefore, maintenance personnel handling
LOX should be immaculately dressed in special clothing; all possible leakage or spillage of LOX
should be prevented; all clothing should be laundered after each occasion of use.
I%es6 procedures- should be followed to avoid inju^ or ac<crdent;-
1 . No equipment oft^fhtia #;at%«ciiE5? f ioiidid' Aould be used *fd^
2. Protective clothing, con^sting of a suitable face shield, a^ron, arid gloves, must be worn
when handling LOX. The extreme low temperature of LOX will instantly produce
painful "cold" bums if it is held in contact with the skin.
3. Bare metal lines containing LOX must never be touched. Bare skin will instantly freeze
to the -297° F metal.
4. LOX must be added slowly to a completely empty system so that temperatures will not
drop too rapidly. Equipment may be damaged by thermal, shock or excess pressure if
LOX is forced in too rapidly.
Oxygen Quantity Gauges. The gaseous oxygen flowing from a Uquid oxygen converter
moves to the pilot under low pressure. The pressure of the gaseous oxygen is controlled by
means of a Uquid oxygen conversion system, which maintains the delivery pressure and volume
by the controPed evaporation of Uquid oxygen. Information on the pressure of the gaseous
Q^sjEpfl. ipt^p 48 piqvl^ed, to the pilot by a panel-mounted pressure gauge similar to the
Tpt^MStt^ g|[UgP«f'WS*WO^i|iiiuid! oxygen, gyatts^ The only difference is the calibration of the gauge.
For a gaseous oxygen system, the gauge is caUbrated from 0 to 1,800 psi. For a low-pressure
Uquid oxygen system, the gauge is calibrated to ce^d from 0 to 150 psi^. Since the pressujre of'
1-48
Physiology bf Fli^t
gaseous o^fgen in th^ liquid Qxy|ett systjeto^iidilniiaUy only itbuiid W|^i the 0 to 150 gauge
penaite easier Madteg of iyslem pi^ . .
An electrical capacitance gauging system gives the pUot an accurate means of determining
the amount of Uquid oxygen remtuning in the converter at any time.
Oxygen Regulators. The oxygen regulator. series several purpq^e^^/It meters the amount of
oxygen suppUed to the user; it regulates the pressure of inspired gas reaching the mask, keeping
it within certain design Umits, and it automatically changes the pressure at which inspired gas is
supplied to the mask in accordance with changes in barometric pressure. In some systems, it
automatically increases the PO2 in flie inspired gas as required by decreasihg barometric
pressure.
Types of Oxygen Regulators, Currently, there are four types of oxygen regulators in use on
Navy aircraft: automatic continuous flow, positive-pressure diluter-demand, diluter-demand,
and miniature 100 percent oxygen demand or the "minireg."
Many older aircraft of i^e transpoitj traiwing, and utility type use the positive-^reggure,
diluter-demand regulator. Only the A-13A inask can be uf?4 Wth type regulator..
Discussion of oxygen regulators will be Mmited to a short review of principles of
diluter-demand regulator design and a much more complex presentation of the minireg which is
in use in almost all of the Navy's fightef arid attaek ^drctEtff 'tod^y. Details of cftHet oxygen
regulators and systems can be found in the Naval Air Systems Comthaiid Manual
(NAVAIR 134-64).
Design Principles of Diluter-Demand, Positive-Pressure Oxygen Regulators. It is possible to
maintain a P02(alv) of approximately 100 mm Hg by adding oxygen to the ambient air in
sufficient quantity to overcome the decrease hi PO2 (alv) due to decreasing barometriopressure.
At 33,000 feet, breathing 100 penlint o«ygeiAv fee barometrfe presgitre is equal tt**i^<ialv) at
sea levels and therefore, P02(alv) b6gin8 to decrease as ascMt ionlfiMEued Aove 33,000 feet. At
39,000 feet breathing 100 percent oxygen, barometric pressure is equal to P02(alv) at
10,000 feet breathing air, so that this is the theoretical ceiling for nonpressurized aircraft using
only a diluter-demand regulator.
Aetualy, the diluter-demand regulator begins furnishing 100 percent oxygen at 27,000 feet
rather than 33,000 feet as noted previously. In addition, 100 percent oxygen can be selected at
sea level, in which case the diluter feature is removed from the system, and 100 percent oxygen
is breathed continuously.
1-49
U.S. Naval Fli^t SsitgeQii's! Manual
Early oxygen systems delivered a constant flow of oxyg^ .tftl^ mask of the ugpf ., ,Thi8 was
extremely wasteful, and the demand system, which delivers oxygen only during the inspiratory
phase, was developed. The regulator senses the slight decrease in pressure as inhalation begins,
and this initiates delivery of oxygen to the mask.
The diluter-demand regulator has several advantages:
' i^i'- It saves oj^^fen iduiii^ alfis|b*€rt»tand deae^« j6ii ilitis prelongs' o3tygMi%iAti©n.
2. It prevents to a considerable degree the development of oxygen otitis media.
3. It prevents the effects of acceleration atelectasis when uted at lowet altitudes during
4. When used at altitudes below 25,000 feet, it prevents the severe drying effects of
100 percent oxygen on the respiratory tract.
5. It has all the features of 100 percent oxygen demand regulators if selected. , , \ ■
6. It is inexpensive. . . ..
Disadvantages of this regulator are:
1. It has a considerable size and weight disadvantage compared to the miniature oxygen
regulato*, at least at ptesent Stage of development.
2. Since the advent of LOX converters, oxygen duration is of less importance than
formerly. '
,3. If ijie cliluter feature is. selected, denitrogenation is not accomplished as rapidly during
dimb-ouj:.
■■*■■■■- ■ r ■. . "J '
4. It cannot be used for underwater breathing if the diluter feature is selected at time of
crash at sea.
Hie 100 Percent Oxygen Demand, Positive-Pressure Breathing Regulator (Minireg). The
]nira?i^''is idso a dAsnd r^lictor but does not have the diluter fea^^s. 0tie ho-ndped percent
oxygfeii fe*Autdniatically delivered to the mask under a slight positive pressure (called "safety
pressure" in diluter-demand regulators) of 1.5 inches of water (2.8 mm Hg) at all flight levels.
The slight positive pressure is beneficial in two ways: It decreases inspiratory effort and thus
lessens fatigue, and it precludes inboard leakage of cabin air or toxic gases.
The increased pressure of oxygen needed at pressure-breathing altitudes is accomplished by
an aneroid. At low altitudes, a small induced leak of oxygen is vented through the regulator. As
altitude increases, the aneroid expands, gradually closing the vent exhaust port. The restricted
flow applies a pressure to the diaphragm by increasing the mask pressure and providing more
1-50
Physiology oi Flight
oxygen. If for any reason the pressure in the mask should get too high, a pressuFe relief valve
opens. It stays open until pressure is reduced.
The regulator operates on 100 percent oxygen at pressures from 50 to 150 psi. With this
inlet supply pressure, the regulator is capable of automatically maintaining a positive pressure
not exceeding two inches of water, for ambient flows up to 100 liters per minute, when
measured at altitudes from 10,000 feet to 35,000 feet. The automatic pressure-breathing
element permits the regulator to deliver positive pressure in accordance with Table 1-15.
Table 1-15
Positive Pressure Loading at 10 LPM Ambient Flow
Sositive preiiure
(Jnehti ef watsr)
Mil
i.o. .
4.0. .
6.0. .
6.a. .
10.0.
3-5 •
S7-
8,0,.,
9,4. .
10. 1 .
10,8.
11,0.
18.0.
Maximum
Altitude
('« feet
35> 000
37. 000
35, 000
40, IQO
4I1 000
ilt 50°
43, coo
0
' 50,000 feet and above, i inch water= 1.87mm Hg.
(NAVAER 00-80 T-51).
Advantages of the miniature oxygen regulator are:
1. Denitrogenation automatically begins as soon as the mask is donned.
2. All takeoffs and landings occur whde breathing 100 percent oxygen.
3. On ejection or bailout, the regulator goes with the pilot, whereas the older, larger
regulators stayed with the aircraft. The pilot thus is automatically suppUed with a
regulated flow of oxygen from the bailout bottle during the entire process of ejection,
rather than an unregulatedj high-pressuTe, continuous flow.
4. An excellent oxygen warning system is inherent in llie design of the minireg. If oxygen
is not being supplied, one cannot breathe. With the diluter-demand regulator, at
altitudes lower than 27,000 feet, the diluter feature would supply air alone if the
oxygen supply ran out, thus giving no warning of hypoxia since breathing appeared
normal. In the event the oxygen supply level of the minireg approaches the usable
1-51
U.S. Naval Hight Sn^eon's Manual
miiiimiim, breathing resistance gradually increases. If this inhaltttisjn resistance went
unnoticed, there would eventually be no flow when the oxygen pressure got helow
15 psi. In such an event, the pilot could simply activate the emergency oxygen cyUnder
and descend safely to below 10,000 feel*
Diaadi^mtages of the minireg are:
1. It requires use of 100 percent bxygen at altitades where breathiftf air would be
physiologicaHy sound/thus causing 6j^|en waste.
2. It increases susceptibility to oxygen otitis media.
3. It increases susceptiBiUty to acceleration atelectasis.
4. It causes severe drying of respiratory epitheUum with some degree of altered physiology
resulting.
5. It is expensive.
For complete information concerning oxygen regulators installed in all Navy and Marine
Corps aircraft, reference should he made to the Naval Air Systems Command Manual
(NAVAIR 13-1-64).
Oxygen Masks. The A-13A Pressure-Breathing Mask. The A 13A pressure-breathing mask is
composed of several parts:
1. Body
2. Inhalation valves (with oxygen)
3. Exhalation valve
4. Oxygen supply hose, with or without minireg , , , ,
5. Nosepiece clamp
6. Face seal , i ,
7. Microphone
8. BlG'SA esonnector (where- miniffegmot instAIled)
9. Suspension system.
The body of the mask is supplied in three sizes: small, medium, and large.
It is imperative that ofily approved and properly fitted oxygeri ^asks Is*! WoWi by fli gh t
personnel. While a FMght Surgeon should know how to fit the mask, the aviation physiologist
and the aircrew survival equipment technician are better qualified and, in most cases, have a
great deal more time available to perform such duties. In testing the "fit" of a mask, the
1-52
Pbyaology of Blight
individual should mount it on his helmet and then expire forcefully with one of the inhalation
valves removed. If the pressure escapes around the face at moderate exhalation pressures, either
the suspension is not tight enough or another mask size is required. At altitude, of course, a
much better seal will he available as the face seal expands, but this procedure is only ug§4 to
check the mask fit, not the ppeSBUSe seal.
If the miniature regulator is not mounted, the inhalation valve should then be replaced and
forceful inhalation attempted with the supply hose kinked above the quick disconnect. If air
leaks in around the sides of the mask, a different size should be selected and tested. If a smaU.
size is selected, one must make certain that the hollows of ^ cheefes do not permit inbctwd
leafesgi^ Amm ii^alafiiw. Ifr fte Ipfe me is selected, one must make certain that the upper
border of the mask body does not seriously impair vision. , i , »,
Inhalation valves, if unseated or dirty, cause exhalation problems, not inhalation problenisj
Exhalation valves, if unseated, may be an unsuspected cause of hypoxia. •>1
The oxygen supply hose is often indicated as the cause of O^gi* Ipfcl'trt t^^^
culprit. It should be examined frequently, however, for leaks or deterioration.
■' The nosepiece clamp should be tightly fastened to hold the supply hose to the mask
nosepiece without leaks. If loose, the hose should be pulled to determine whether the "ton|ue"
of the supply hose is still fitted iiiside tiie *'groove^^Ctf th&fflo#pieGe. ;0ecisii$ft
be found with the clamp t^htly fastened around the hose itself and not around the mfptf
hoae-nosepiece junction. This can be a fatal configuration if undetected. The clpnp fasteWg
the hose to the minireg should be checked for tightness and point of application.
The MC-3A connector is used on the distal end of the supply hose when the miniature
regulator is not fitted to the maisk and a console-mounted regulator is utilized. It fcas a
connector for bailout oxygen supply, connector for aircraft oxygen supply, a webbing strap for
connection to the parachute harnep, a warning device for unsuspected quick-disconnect
detachments, and an attachment to the supply hose. The aviator must be instructed to utiHze
the webbing strap, placing it under the shoulder straps and attaching it to the parachute harness.
If he does not, bailout will result in the supply hose being stretched until the quick-disconnect
fitting gives way, at which time ^e disconnector may be slammed,into tfee eraator's face by the
supply hose.
When the mask-mounted miniature regulator is employed, the nosepiece is nonelastic but
flexible; the connector is fastened to tke bailout bottle in the ridged sfeiltWV^aa Mt; «fcl ft^
strap is needed.
1.53
U.S. Naval FK^t Surgeon's Manual
The oxygen flSis©! Sttspaljibjri ^simi i» careftttty eti^eferfetf'fdr mmf qttMties. It is far
superior to those in use on the same mask just a few years ago. Rarely are reports seen today of
hypoxia suffered by an aviator due to displacement of the oxygen mask during the accelerations
of a gunnery run or an aerobatic flight. The suspension is even tested for its ability to resist a
windblast of over SOO knots while attached to the helmet without failure of any part.
Dysbarism
Dysbarism is of interest to a Flight Surgeon for several reasons. He must be able to recognize
aHifl cope with dysbarism incidents occurring in altitude chamber training as well as in actual
fli^t operations. Dam^age to aircraft resulting in rapid decompression may be a cause of
dysbarism. The training responsibilities of the aviation phygiologik inelu€e 0ontintt<ws
instruction of aviators in the causes, effects, and prevention of dysbarism. Sea-level barometric
pressure is simply one point on a continuum of pressures ranging from near zero in outer space
to the high pressures associated with deep submergence. Naval personnel may be exposed to all
of these extremes of environment and must either adapt physiologically or be adapted by the
design of their life support equipment.
Dysbarism consists of those disturbances in the body, exclusive of hypoxia and airsickness,
which result from the existence of a pressure differential between the total ambient barometric
pressure and the total pressures of dissolved and free gases within the body tissues, fluids, and
cawties. In altitude dysbarism, the total change in pressure is less than 760 ram Hg.
Qassifieation of Dysbarism
AU symptoms of dysbarism may be considered as being due to the pressure effects of either
evolved or trapped gases. However, another classification divides! all such symptoms into those
due to hypobarism and those due to hyperbarism.
Hypobaric effects result from gas pressure within body fluids, tissues, or cavities which is
higher than amibieiit pressure. Ttiese effects are subdividetl into tfie evolved-gas types and fiie
trapped-gas types. Examples of the evolved-gas types are (1) the bends, characterized by joint
pains caused by cvolved-gais bubbles within tJie joints; (2) the chokes, with cough, chest pain,
and dyspnea due to pulmonary intravascular evolved gas, as well as mediastinal emphysema
from evolved-gas bubbles; (3) central nervous system symptoms caused by evolved-gas pressure
on or in the brain and spinal cord, as weO as embolic phenomena, which sometimes may be
e^iUed itt^e!ra# ,aBid.(4);^iii disturbances |t|»e itcb^e8^)j,4ue tp evolved-gas bubbles under
the skin and to neuroqitculatory phenomena due tO J^uhlile preipare 04 peiipSNfral rierves and
blood vessels. Trapped-gas types consist of abdominal distention and barodontalgia.
1-54
Physiology of Plight
Hyperbaric effects result from an excess of ambient gas pressure over that within the body
fluids, tissues, and cavities. Examples are barosinusitis (aerosinusitis) and barotitis (aerotitis).
In this classification, both hypoharic and hyperbaric effects could be suffered on a single
flight, The hypoharic effects would be noted on ascent, and the hyperbaric effleots on dfeseent,
since the gases In the body fluids, tissues, and cavities are changed during the stay at altitude
from those at sea-level pressure. Hyperbaric effects would, of course, be noted on any descent
below sea level, and hypoharic effects would occur on the ascent ironi any depth below sea level
to any lesser depth. Hypobarism is the major aspect of dysbarism with which this section is
concerned.
Etiology
In discussing the etiology of hypobarism, the effects, as noted above, may be divided into
those due to evolved gases and those due to trapped gases.
Evolved Gases. Any tissue in which a dissolved gas is saturated may become supersaturated
with a rapid decrease in ambient pressure, thus causing bubble formation. Although nitrogen is
the gas impHcated in almost all cases, oxygen and carbon dioxide can form bubbles HHd thai
cause dysbarism. Also, a nitrogen bubble, once formed, may become filled with a different gas
(such "O^Kygett, water vapor, or carbon dioxide) by diffusion into the bubble. Hypoharic
effects in the human due to evolved gases may be considered as being due to the effects of the
intra- and extravascular formation and expansion of bubbles of nitrogen caused by the decrease
in ambient pressure incident to ascent to altitude.
The total amount of nitrogen normally in solution in the body is 1,000 to 1,500 ilriililiteBli
representing saturation of the tissues with this gas at sea level. Almost all of this is in solution in
the tissues, with a comparatively small amount in solution in the blood. ■
Nitrogen is a metabolicaUy inert gas. While carbon dioxide and oxygen are transported in
the blood both in eheniical coiHbination and in solution, nitrogen is transported only in simple
solution according to Henry's law. Nitrogen enters into, and is removed from, the body by the
establishment of an equilibrium between nitrogen pressures in the alveolar air and the venous
blood, and another between the pressures in the tissues and the arterial blood.
When ambient PNg is reduced, as during ascent, nitrogen transport is directed toward
removal from the lungs. The tissue PNg is higher than that of the arterial Mood, so tissue
nitrogen is lost to the blood, and thus to alveolar air and eventually to OtttSide, Hdfweyet, only a
finite amount of nitrogen can be transported by a given quantity of blood,.and, if the ambient
1-55
U.S. Naval Fli^t SuigeoiiX Manual
pressure is reduced too rapidly, the tissue nitrogen cannot be transported rapidly enough. The
formerly nitrogen-saturated tissues then become supersaturated, with the result that bubbles
form in the tissue.
Nitrogen bubbles may form in futiy tissue including th» Ijloftd. The pljMlf ,qI ^|t©flj-ance, and
the size of the J^ujfefele^ determine the specific typ.s _fl[| pathology and thus the resulting
^mptomatology. 'I . ' ■ , .
Trapped Gases. Etiology and symptomatology of hypobaric effects on humans due to
trapped gases result from their expansion due to the decreased barometric pressucf: ^S^iy^il^
aits^nt to altitude and the resulting pressure phenomena on the involved viscera and adjaeent
organs. Effects on the sinuses, ears, and teeth are covered in detail elsewhere. The only
trapped-gas effects to be discussed in this chapter are those due to expansion in the hollow
abdominal viscera.
Predisposing Factors
Any cause of increased tissue nitrogen tension or decreased excretion rate may predispose to
dysbarism -*li«RuamMfent pressure is reduced. A rapid ai^fat may cause (dy#>aplssn in the face of
normal tissue PN2 and normal excretion rates. The whofle matter is made more difficult by the
existence of marked individual variance in susceptibility tP hyB##i¥>ni;JRd'ewn d^Kerencesin
the same individual from one exposure to another, • 1 ,
Any individual wiU experience dysbarism if he makes a rapid ascent to high altitude and
then exercises. The purpose of this section, however, is to present the factors which facilitate
the appearaiBoe of .dysbarism without such a^avation.
Age. While it is generally agreed that the risk of dysbarism increases with advancing age,
there is not a direct relationship. However, as age increases, so does weight, and the muscle/fat
ratio changes »alia. Such gefteiaUliei wwot he used to specify risk in a particular case, but only
in age groups. Table 1-16 shows the relationship between age and siifi^pl^ility to )^fifl*Kj9jd
hypohaiiswt i ' ■
Obesity. Fatty tissue is less vascular than muscle tissue. Nitrogen transport, therefore, is
slower firom fat tissue to blood than from muscle to blood. In addition, nitrogen is five times
more soluble in fat tha^,in ^vate% Uw®) a* «fWlih)WP) %ttf tissue has five times more nitrogen
iJxan Hood or musol^ Qnnerally speaking, the more Q^ff ig||ip% tl^f fp^te^ ^
probabUity of dysfeiBpe*. ' - S-o. ; . . • 1
1-56
Physiology of Flight
Table 1-16
Relationdbi^ Between Age and Susceptibility
in Subjects Exposed to 28,000 Feet for 2 Hours
Age Group
Total
numter
Number With
symptoms
Percentage
susceptible
17-20
642
9
1.4
21-23
600
17
2.8
24-26
482
37
7.7
27-29
296
32
10.8
30-35
385
31
8.1
36+
230
20
8.7
Total
2,635
146
39.5
(Fryer, 1969).
Exercise. At altitude, exercise definitely increases the incidence of dysbafism. Figure 1-11
shows the relationship between duration of exposure, amount of exercise, afld symptom
incidence. The reason for this changed incidence is not definitely known, but it is thought to be
due in part to the increase in tissue metabohc carbon dioxide incident to the exercise.
Rate of Ascent. Haldane's work (Frj er, 1968) showed that stepwise ascent from depth (in
water) was feasible, and that it was practical to decompress a man directly to a point at which
the total pressure was not less than half the presgure of dissolved nitrogen in the tissues.
Therefore, Btti of asemt within this hmit would theoretically have no effect on incidence of
bends, but rate of ascent outside the limit would. Although these observations are the
foundation of divers' decompression tables, their apphcability to aviation medicine is open to
some question. Indeed, Fryer (1969) suggests that rate of ascent is not a causative factor, and
that it should be kept high to minimize the time of exposure to decreasing barometric pressure.
During ascent breathing 100 percent oxygen, denitrogenation is being accomplished, so that rate
of ascent does have some effect.
Attained Altitude. Figure 1-11 indicates the altitudes at which dysbarism becomes a
problem. In the hterature, it is relatively rare at altitudes below 25,000 feet, although
Fryer (1969) has reported a case at 18,500 feet. Seventy -five percent of the problems are at
altitudes greater than 30|000 feet, according to data presented by Bs^on, Pheeny, and
Dully (1976),
1-57
U.S. Naval Fli^t Surgeon's Manual
ALTITUDE, ft X 1000
.. 40 38 36 34 32 30 26 26 24
70n 1 1 T r 1 ■ (— — — i 1
BAROMETRIC PRESSURE, mm Hq
Figure 1-11. Comparison of the incidence of decompression sickness during exposure
to various attitudes for two houra with md wMioat esercise (Fryer & Roxburgh, 1965).
Certainly, if the bubble theory is correct, the greater the aWtude, fte largei? 'lie biibbte. lt
has been previously noted that at 18,000 feet, the barometric pressar^^ oMly half that at sea
level and is, therefore, roughly at Haldane's upper limit for safety. '
Inmased Tissue PN2 Prior to Jl^nt, Hie im of increase in barometric pressure in water is
extrtody rapid wfeen compared with the rate of decrease in the atmosphere. A descent of only
33 feet wiU cause the barometric pressure to be doubled to two atinOi|ira'e8, whereas an ascent
from sea level up to the edge of the earth's atmosphere at 200,000 feet changes the barometric
pressure by less than one atmosphere. A descent of only 132 feet will produce a fivefold
increase in pressure.
When breathing air at these increased pressures, the partial pressures of the constituent gases
show a comparable increase. For example, at a depth of 100 feet (four atmospheres), five
percent oxygen is etjuivalent to 20 percent oxygen at sea level. However, such a PO2 probably
1-58
Phyfflology oi Flight
would not used inasmuch as ascent would rapidly render the individual hypoxic, unless the
PO2 were increased in direct proportion to the pressure decrease.
Similarly, two percent carbon dioxide in a mixture inspired at 132 feet (five atmospheres)
will produce the same physiological effects as ten percent carbon dioxide inspired at sea level,
i.e., it win cause unconsciousness. Therefore, all metaboUc carbon dioxide must be vented
overboard or absorbed in underwater work.
Most importantly, the effect of increased barometric pressure on nitrogen must be
considered. When a person resides at sea level, his blood and all his tissues become saturated
with dissolved nitrogen at a tension equal to PN2(alv). With an increase in barometric pressure,
the PN2(alv) increases and the saturation levels of blood and tissue increase proportionately
according to Henry's law. For example, in an exposure to a depth of 132 feet (five atmospheres)
breathing air, the total nitrogen in solution in the tissues will be five times as great as that at one
atmosphere if sufficient time is allowed to achieve saturation (up to 12 hours). In concrete
terms, this means about 5,500 to 7,500 milliliters of dissolved nitrogen is in the tissues at
saturation. When the individual begins an ascent, it must be undertaken in Steps according to
Haldane's formulae and more recent Navy diving tables {U.S. Navy Diving Manual, 1973) or else
must be performed so slowly as to be impractical. If the ascent is performed in any other way,
the tissues reach supersaturation with nitrogen, due to the inabihty of normal respiratory
washout to keep pace with the large quantities of evolved gaseous nitrogen. Bubbles then form
and dysbarism occurs in its classic forms.
Scuba Diving Versus Altitude Dysbarism. Of particular interest is the relationship between
scuba diving and susceptibiHty to dysbarism during high-altitude flight. Dysbarism is
infrequent below altitudes of 18,000 feet. However, an instance in which several members of
the crew of a civiBan airliner developed disturbances at an altitude of 7,000 feet has been
reported (Furry, 1967). Investigation showed that all bad been scuba diving immediately
before the flight. For this reason the NATOPS requires all aircrewmembers participating in
scuba diving to adhere to the following rule: "Under normal circumstances, personnel shall
not fly or perform low pressure chamber runs within 24 hours following scuba diving,
compressed air dives, or high pressure chanber runs. Under circumstances where an urgent
operational requirement dictates fH#lt, personnel may fly within 12 hours of scuba diving,
providing no symptoms of aeroemboUsm develop following surfacing and the subject is
examined and cleared by a flight surgeon" (OPNAVINST 3710.7H, 11 September 1975.,
page 7-7).
The physiological reason for this rule is that enough time must be allowed at sea level,
breathing air, to complete respiratory washout of the exmss nitrogen stored in the tissues
1-59
U.S. Naval Ki^t Surgeon's Manual
during the dive. "Excess" is defined as that amount present over and above that required
to produce nitrogen saturation at one atmosphere.
Decreased PN2 Prior to Ascent. Experimental work on inhabitants of mountain villages
(Hurtado, 1964) has shown that they have far less decompression sickness than persons dwelling
at sea level for similar ascents. This is prdbaBly due to tiieir decreased tissue PN2 as a result of
natural denitrogenation.
Other Factors. Other factors affecting altitude dysbarism are listed beloWJ
1 . Previous injury - Bubbles tend to form at sites of recent injuries in some eases.
2. Repeated exposure - Individuals who have once had an attack of dysbarism may be
more susceptible to another such attack.
3. Total dissolved-gas tension has been imphcated as the cause of dysbarism, rather than
amply nitrogen terision. This would account for the increased incidence following
exercise.
4. Dysbarism occurs with greater frequency at lower atmbieht temperatures, possibly due to
decreased nitrogen transport associated with peripheral vasoconstriction due to cold.
Qinieal Features
Hypobarism (Evolved-Gas Type}. Bends is defined as a clinical manifestation of hypobarism
consisting of pain referred to the joints, muscles, and long bones. It customarily appears after an
ascent but usually after a lag period of variable length. The site of appearance is most often the
knee, followed by the shoulder, then the elbow, wrist, hand, and fingers in decreasing order of
frequency. The pain may become worse or better with time and may even disappear. This is the
most frtSquenfc tyye of evolved-gas hypobarism. Bends is not considered a serious condition
perse and is uBUafly feJieved by deaeent. The theoretical causal mechanism of bends is
formation of nitrogen bubbles in periostiai' Vessels^ fn infea-articiilai* fat atid fluid, and in the
muscle and fascial planes. I
Chokes is defined as a form of hypobarism characterized by substernal distress,
l®a^t<>ductive cough, and difficulty in toeathmg, accompanied by a sense of apprehension find
saflocatlorn. Chokes is a more serious condition than simple bends. Theories of precise etiology
are numerous and probably all have some basis in fact. However, almost all the symptoms can
be explained as due either to the formation or collection of bubbles in the puhnonary
capillaries, and/or to the effects of extravascular mediastinal bubbles exerting pressure on
mfttstiiiaa contents and adjacent puhnonary tissue. Chokes may occur as the only symptom,
but.ffltost often it is associated with bends. When an individual develops both symptoms, the
1-60
Physiology of Flight
chokes usually appear later in the flight than the bends. Chokes tend to prQiress more than
hends and be. Hiore disabling.
Cough and substernal distress in chokes are both roajkedly aggravated on attemptu^ to -take
a deep breath, whiofi lesalts in decreased puhnonary ventilation and lhW» h^rpe^a. It is not
surprising, th^are, th*t s)rncQpe and coUapse are more frequent than in bends. In fact, onset
of chokes should bf regarded as an emergency requiring immediate recognition and action
consisting of prompt descent, termination of an altitude chamber or aircraft flight, and
recompression therapy.
Central nervous system disorders m another form of hypobarism. Bubbles fowgd
anywhere in the body can todg# ia the arterioles or capillaries of the brain caupag almost any
central nervous system disttifbance imaginable, depending on bubble size and location.
Secondary vasospasm may occur, resulting in even greater severity of manifestations. The usual
central nervous system symptoms are referrable to the senses, especiaUy vision, and to
disturbances in orientation. Any central nervous system symptom is an in^e^tton 103? mw^tfl;^
hospitalization and immediate recompression therapy. Nevertheless, most, if not aU symptoms
of central nervous system dysbarism, disappear on the recompression incident to descent to sea
level.
The reason for hospitaUzing all aircrew or altitude chamber personnel who have had an
attack of central nervous system hypobaric effects m that at various unpi^dietahle timi» after
complete recovery, sudden and severe neurocirculatory coUapse m^ oei?UE wifeno wajining.
The incidence of central nervous system symptoms is low, and the effects are temporary, but a
high level of awareness is needed in dealing with in-flight incidents. Otherwise, the temporary
visual defect which disappears on descent, or the staggering gait which may be the only effect
noted, will be assigned to other causes or summarily dismissed.
Hypobaric collapse is discussed in Randel's Aerospace Medidne (1971). In about teri
percent of the cases of severe bends and 25 percent of cases of chokes, syncope occurs.
Furthermore, shock may result from the syncope and that may progress with
hemoconcentration or neurocirculatory coUapse. Little is known about hypobaric coUapse
except that it does occur; it is usually but not always preceded by bends or chokes; it is more
frequent later in a flight, occurring usuaUy after bends and/or chokes; frequently it follows
central nervous system manifestations, and it may have no premonitory signs or symptoms at
all.
As an example, a rather obese Chief Petty Officer noted visual Eusions consisting of "bri^t
spots before tiie eyes" during an altitude chamber fli#it, with no other complaints or findin|s.
1-61
U.S. Naval Flight Surgeon's Manual
Immediate descent caused alleviation df all ^Mpfoms, and the indMM wks qtlite hostile to
the idea of hospitalization. He was transported to the hospital lying down, protesting all the
way, and was admitted with no presenting complaint. About one hour after admission and two
hWirs after the original complaint of mild visual iUusion, the patient suddenly went into
profound shock with no obtainable pulse or blood pressure. Einergency therapy was ready at
the hedtde for just meh m eventuality, and the patient recovered after an agonizmg half-hour
of treatment. He was observed for 48 hours thereafter and then discharged with no complaints.
Such a reaction in an aircraft or at home might well have proved fatal.
Skin manifestatioHs may result when nitrogen bubbles occurring intra- and extravascularly
cause pressure phenomena on dermal nerve endings, adjacent nerves, and blood vessels.
Subdermal emphysema is a frequent oecurrence and is easily identified by the crepitation on
palpation. Formication is frequently reported, along with skin rashes, mottling, itching, burning,
and skin paresthesia and anesthesia. These manifestations may occur as the first sign of
evolved-gas hypobarism, but they usually disappear without sequelae on descent. They do,
however, represent a Warning of bubble formation and therefore are a danger sign.
Hypobarism (Trapped-Gas Type). Gas trapped in a hollow viscus wiU expand when the
ambient pressure is decreased, doubling its volume at 18,000 feet and quadrupling it at
33,000 feet. The usual locations causing difficulty are the stomach, small intestine, and colon,
including the rectum. Figure 1-12 presents the incidence of abdominal fullness or pain reported
by subjects during decompression to high altitude. It shows the increase in symptoms to be a
roughly predictable function of the decrease in barometric pressure.
When gas is in the stomach, eructation usually brings immediate relief, but if the gas
pressure is not removed or reduced, a diaphragmatic herniation may be produced. Shock due to
gastric dilation can also occur.
the colon, gas expansion due to ascent produces the usual symptoms of flatulence, and
expulsion of the gas brings immediate relief. If for any reason the gas is not expelled, symptoms
of colonic distention will be noted if the pressure is decreased sufficiently or if the initial
amount of gas is sufficiently large. The pain can even be coliclike and cause a generalized
vasomotor reaction characterized by pallor, diaphoresis, and syncope.
In the small intestine, trapped gas reacts in a similar way, bwt it is difficult to remove by
either route. To make matters worse, gases in solution in the intestinal contents tend to come
out of solution when the ambient pressure is decreased, thus adding evolved gas to the trapped
gas in the intestine. As in all instances of trapped-gas syndrome, the treatment is descent to sea
level, but recompression therapy is not indicated.
1-62
Physiology of Fli^t
1.0
ca
CN
>
P1+P1.
'la
0.6 -
0.2
-V,, [BPTS]
0.157
0,111
__J lO
760
_L
600
400
PRESSURE (mm Hp)
10,000
18,000 25,000
200
0)
u
O
I-
o.
S
u-
O
>-
o
z
UJ
O
40,000
Fimire 1-12. Incidence of symptoms of abdominal fullness or pain (circles) during slow
decompressions, versus average increase in intestinal gas volume at mdicated pressures
(Billings, 1973b).
Differential Diagnosis
Evolved-gas hypobarism occurs after an ascent, whether from depth to sea level or from sea
level to altitude. Therefore, a history of exposure is a prerequisite. ThereaFter, many of the
effects of hyperventUation, hypoxia, and evolved-gas hypobarism overlap. Differential diagnosis
between hypoxia mA hyperventilation is given elsewhere. The m^or point in differentiating the
chokes from hyperventilation is that observation of deep breathing is almost defmitive m
hyperventUation and hypoxia, whereas it aggravates the chokes and therefore is not seen. The
chokes may be differentiated from acceleration atelectasis by history of onset of the former
foUowing simple ascent to high altitude, while the latter usually fallows
tion-producing maneuver at lower altitudes and can be demonstrated radioraphic^ffly. 0t)l0r
differentiations are more difficult because the basic pathophysiology in evolved-gas hypobarism
• is tissue hypoxia due to arterial occlusion by bubbles. The differential diagnosis would appear to
be easy when recompression causes immediate and complete relief of symptoms, but
recompression also brings increased POg. Therefore, the differential diagnosis must He
1-63
U.S. Naval flight Su^eon's Manual
considered as one of exclusion. If the incident occurred after an exposure to an altitude of
18,000 feet or higher, and if the oxygen supply was not interrupted or insufficient, a
presumptive diagnosis of evolved-gas hypobarism may be made.
Bends Hay be confused with muscle or jd&t sirain. W&ldly, external iw^ence of trauma
would tend to rule against bends, but conversely, bends fe knoinEi to oeoiir mote frequency in
recently injured joints. The acid test in this case is recompression to sea level which wffl almost
always alleviate the severe bends pain but will have no effect on injury pain.
The paill of trapped gases may be confused with that of an smte surgical condition of the
abdomen. \^en expulsion of gas relieves the pain or neurological disturbances of any type are
present, there is sufficient reason to descend to a lower altitude and, in the majority of cases, to
terminate the aircraft or altitude chamber flight.
Clinical Management
Evolved-Gas Hypobarism at the Altitude Chamber. One of the primary responsibilities of a
Flight Surgeon is to provide medical support during altitude chamber runs and to administer
emergency treatment in the event a decompression reaction is experienced in personnel within
Hie ehamber. The UtiUzatha BmtllmA for 9A9 lists procedures to be followed by
chamber-operatij^ pmonnel and the Flight Surgeon.
Prior to all chamber flights, the clinic or hospital is notified that the altitude chamber will
be in operation. This information is passed on to the duty Flight Surgeon who is then able to
observe the actual chamber flight or is, at least, alerted that su<& training is in progress. During
the chamber flight, participants should be cautioned to repoM any untsiial symptoms
immediately to the inside instructor. In the event of a chamber reaction, the du^- Jl^t
3urgeon,is, C4lled upon to render assittatMse.
The initial treatment of possible severe decompression -factions is recompression, by
descent. If in doubt as to diagnosis, deseeitt iS sM indicated. The rate of descent has to be
governed by each individual case and will depend largely upon the severity of thfe¥6a^ti6ft. If
the reaction is mild, a gradual descent is permissible, although, if above 30,000 feet, descent to
about 20,000 feet should be made at free-fall rates. If the reaction appears to be serious, rapid
descent to ground level may be indicated in spite of discomfort to other occupants. However,
one must not fail to observe all other occupants. In all cases of collapse, a horizontal position
with feet elevated is desirable. An open airway is maintained and tOOperceni oxygen is
administered throughout the descent. If apnea exists, artificial respiraticto is; of coufse,
mandatory. Cardiopulmonary resuscitation procedures must be impleiiiehtfcd as required.
1-64
Physiology of Flight
All personnel who experience altitude chamber reactions must be referred immediately to a
FUght Surgeon for postflight examination and disposition. The FUght Surgeon must appreciate
that most persons suffering mild chamber reactions will have no sequelae. However, if a bubble
remains, even though decreased in size, its effects on circulation will be detectable on physical
examination. Central nervous system effects noted during a chamber run make hospital
admission mandatory in every case, as a precaution.
Evohed-Gas Hypobarism While Airborne. OPNAVINST 37X0.7H states, "When an occupant
of any aircraft is observed or suspected to be suffering the effects of decompression sickness,
the pilot will immediately descend, land at the nearest installation, and obtain qualified medical
assistance. The person affected may continue the flight only on the advice of a flight surgeon."
Evolved-Gas Hypobarism Postflight M with hypoxia, most of the symptomatology is
alleviated by descent. An occasional individual will continue to have complaints and exhibit-
physical findings. One must remember that confusion and disorientation are prominent findings
in cerebral hypoxia, whether caused by low PO2 (hypoxic hypoxia) or by occlusion of the
arterial blood supply (stagnant hypoxia) by bubbles. Therefore, any person suspected of having
suffered decompression sickness (evolved-gas hypobarism) should have a thorough history
(including mental status) taken, preceded by a thorough physical and neurological examuiation.
The inver&e order of examination, foUowed by history taking, is necessary to detect residual
effects before they disappear. The symptomatic case should be treated differently, however, and
should be immediately placed in a recompression chamber, if available. If the patient is unable
to speak coherently, another crewmember should be questioned as to the circumstances of the
flight and the onset of the disease while treatment continues. Immediately requued facts
include time of takeoff, rate of climb, attained altitude, lengtii of time at altitiide prior to onset
of disease, changes in cabin pressurization, precise and inclusive symptoms noted, any tiansient
paralyses or other signs of neurological involvement, and disturbances of consciousness.
Any individual showing central nervous system symptoms, such as the bends, even though
all symptoms may have subsided, should be admitted to the hospital for at least 24 hours and
observed clo«ely during this period. There may be a delayed onset of severe neurocirculatory
collapse. Even though the examining physician finds the subject to be symptom-free, he should
be hospitalized for this period, with preparations made for the eventuality of recompression m a
hyperbaric chamber.
Diagnosis should be based on:
1. history of exposure
2 symptoms suggestive of neurologic involvement, such as numbness, paresthesia, and
motor weakness. In severe cases, cerebral symptomatology and coma may predommate.
1-65
U.S. Naval Flight Surgeon's Manual
3. vascular instability and syncope on standing, which should alert the physician to
^m^mm mm^s. Blood pressure usually is iHaintained for some time after much
pteitia fe test, Shoik has sudden onset in these cases.
The following base line data should be secured:
1. Body weight
2. Hematocrit
3. Hemoglobin
4. Complete blood count
5. Plasma volume and red cell volume
6. Serum electrolytes
7. Electroencephalogram
8. Efeetroeaidis^am
9. Intake and output. Establish a strict record to include an hourly urinary output through
an indwelling catheter.
Maleitfe, Fitzgerald, and Cockett (1962) suggested treatment procedures for dysbarism while
pteiaeiiig the listing of prodedtlres T^th to eaution "a typical case of dysbarism presents a
mistture of ngutologic and hypovolemic symptoms. A high degree of dinical judgment is needed
to assess the predominant lesion. Much critical analysis will have pi^ieede ktelMgent therapy
in each case. Proper weight must be given each symptom and findil^ in the estimate of the
clinical situation and therapy directed in a logical manner." They recommend the following
protocol in the management of altitude dysbarism of the central nervous system:
a venous fluid pathway.
2. Calculate static plasma deficit and begin replacement of plasma volume. Avoid
vasopressors.
3. Maintain urinaly output of 35 ml per hour as nuoimuin.
4. After initial plasma replacement, repeat hematocfit and recalculate deficit for
continuing loss.
5. Follow patients with frequent ehet^ of respiration and breath sounds.
6. As hematocrit approaches normal levels, begin balanced administration of fluids other
llian plasma to cover intake and output.
7. As diuresis begins and urinary output increases above 50 ml per hour, st^t daily
maintenance fluids. (By this time, the patient may be maintaitted.on oral intake.)
8. Maintain strict bed rest until patient gives both clinical mi laboratory evidence of
recovery.
1-66
Physiology of Flight
Most hospital medical staffs are usually not prepared to deal witji CoHaj^iSfe due to
evolved-gas hypobarism, in that it OB both rate aMd serious. The Il#it Surgean #iOuld be aware
of the disordered physiology, diagnostic aspects, and what is known of therapfifUtics f or this
condition.
Compression Therapy
In instances of mUd decompression sickness, symptoms typically are promptly and
completely relieved by recon.pression to sea-level atmosphere. In more serious cases, however,
the reaction continues unabated when the individu4if returned to ground-level pressure. If the
episode is due to the release of nitrogen bubbles, the question then arises as to v*y descent to
ground level does not in these instances cause the bubbles to go again into solution.
Experiments with human serum in a smaU pressure chamber showed that when pressure
above the serum was reduced to an altitude equivalent to 43,000 feet, bubbles evolved; when
the barometric pressure was brought back to ground level, the bubbles markedly decreased in
size but did not disappear. The chamber atmospheric pressure then was further incrmsed to
75 psi. At this level, the bubbles decreased much more in size, with many but not all of them
having disappeared altogether. This study provides a rationale for the use of overcompression in
the treatment of dysbarism (Downey, Tracy, Hockworth, & Whitley, 1963).
Donnell and Norton (1960) report the successful use of the compression chamber in
treatment of an instance of severe decompression sickness witn neurocirculatory collapse. In
this case, the patient, who was moribund, was placed in a compression chamber approximately
five hours after the onset of symptoms. He was subjected to a pressure of six atmospheres,
corresponding to a depth of 165 feet of sea water. On reaching this pressure 14 minutes after
leaving the surface, the shock condition began to disappear. Blood pressure improved and
stabilized at 110 mm Hg systolic pressure. The patient was kept at this pressure level for two
hours and then gradually decompressed over a 38-hour period. During tills prolonged slow
decompression, impovement was gradual but sustained. Upon leaving the chamber, recovery
was virtually complete.
Goodman (1964) provides a report of 14 successful cases of treatment of dysbarism through
overcompression. In this review, it is suggested that successful clinical experience with
compression is itself an etiological argumait for the bubble hypothesis of dyahansm reaction.
Goodman also feels that the experimental obgervations of bubble formation, combmed with the
successful cUnical experiences, advocate the early institiition of additional applied compression
and condemn a purely supportive regimen.
1-67
U.S. Naval Flight Surgeon's Manual
Based! on the 14 successful experiences, the following conclusions are drawn:
u..%,'^.mm^-mom^Mon is MtiSted after an episode, the better are chances for
: j^^plete recovery, ^ ■■ , . , <
2. With a delay of two hours or longer before compression, use of Navy Treatment Table 3
or 4 {U.S. Navy Diving Manual, Table 1-21, 1963) wiU ultimately be followed by
recurrences and/or residual effects.
3. In severe dysbari^ with delayed institution of compression therapy, the use of oxygen
is indicated.
4. For cases not notably complicated, the depth of compression required for ^ptom
remtsmott die>6s not exrceted three atmospheres absolute.
TaBle 1-17 presents compression profiles considered both optimal and safe for normal and
difficult recoveries.
Trapped-Gas Hypobamm (Boyle's Law). If pain or other severe symptoms occur and cannot
be relieved by expulsion of the gas one way or another, descent from altitude will alleviate the
dltahyv'freiju^nt cau^g of intestinal gas distention are dietary factors, aerophagia, and
intestinal upset.
Dietary factors known to be important in producing abd^tnM^'^aistf at altitude are
gas-forming foods, foods which contain gastrointestinal irritants, find foods which produce
aUergic reactions in particular individuals. In general, it has been found that high-carbohydrate
meals are more likely to increase gas volume than high-protein meals. Melons, carbonated water,
and beer produce gastrdiintestinal bloating at altitude.
Gastrointestinal irritants may include spicy foods, condiments', omolisi beaas, cafcliage,
peanuts, peppers, and cucumbers. Such foods do not necessarily contribute to the gas volume'
but they do produce increased abdominal distress through alterations in the sensitivity and
Motffity^xftheliieslinaltra^^ • •. •
Any cause of aeropfeagiS lnt«Be^C(ided. Therefore, aircrews should havfe the opportunity
to eat a leisurely meal in quiet, relaxed surroundings prior to a flight. Chewing gum should be
avoided both before and during flight.
Any gastrottitestinal upset causing diarrhea, nausea, or vomiting may also produce larger
<pWttisi of intestiiial ps tiian normal aiid may inisifere wWi fiSriKal expulsion. For this
reason alone, aviators with itttestiB^%pe« A<jul# be grounded until recovered. Another reason
is that electrolyte disturbances which are commonly associated with gastrointestinal iWt^ility
may cause severely decreased capability in reacting to stress, whether induced by acceleration,
heat load, or the exertions of escape and evasion.
1-68
Table 1-17
Recommended Com|)*essioii Prem for Momal Recowries and for Those Wfth Pems«ng Sympt.
PARAMETERS FOR MINIMAL COMPRESSION-OXYGEN BREATHING THERAPEUTIC
Treatment phase
Depth (feet)
TiDic
(minutes)
Total time
(niinntesj
Gas
Remarks
0-60
1
Oxygen
Rate variable.
60
go
60
10
16
z
ir
38
40
Oxygen
Oxygen
Air
Must be complete; use tabic B
if symptoms persist.
60-58
1
4i
67
Air
Oxygen
Uniform ascent, i FPM.
53 ; 3°
97
Oxygen
Uninterrupted.
33-0
33
130
Oxygen
Uniform ascent, i FPM.
B. METHOD FOR PERSISTING SYMPTOMS FOR MAXIMAL, SAFIB USSEIE R1£S^YGBNATI0^
J
o-€o
2.
• 1 ■
Ojtygen
Rate variable.
Breathing mixnire alteis^on pattern for 6o-fcet exposure
60
60
6q
60
x8
15
z8
30
45
73
75
Oxygen
Air
Air
Interspersed air breathing
prolongs OHP preconvulsive
latency.
60-58
58-33
77
100,
Air
OjEygen
Uniform ascent, i FPM.
Breathing mixture alternation pattern for 53-fcet esposon: . . . .
33
33
33
.»
15
60
15
60
177
Air
Oxygen
Air
Oxygen
Interspersed air petiods for
comfort; tattendauts on air
entire 185 minmesj!.
lie.
u
18s.
Oxygen
Uniform ascent, i FPM.
(Gooilinaii, 1964.x
U.S. Navid Plight Surgeon's Manual
Intestinal upsets are relatively frequent in foreign shore areas, especiaUy in advanced Marine
Corps bases under combat conditions. A Flight Surgeon must remain alert to the incidence and
preyalence of such cdttditiofls becatise mme aviators consider them unimportant and do not
report to eiekt^, Goiisid^able effort in obtaining good food and water sanitation is justified in
order to maintain combat readiness of aircrews.
Prevention
Denitrogemtion ("Nitrogen Desaturation" or "Preoxygenation"). One method for prevent-
ing evolved-gas hypobaric effects is "denitrogenation," or removal of all dissolved gaseous
nitrogen in the body. Denitrogenation is accomplished by establishing a "gradient," or nitrogen
partial pressure difference, between the tissues and the alveolar gas, such that alveolar PNg is
low. Tissue PNg, 'torefCae, diffuses readily to bteod and tos to alveoll If the extepior supply
of nitrogen to the alveoU is kept low or non-existent, and if the exhaled gas is vented, eventually
most of the tissue nitrogen can be removed. The time required is the same regardless of the
original gradient.
A limiting factor on nitrogen excretion is pubnomry washout rate. In the example given in
Comroe (196S) of a. man given 100 percent oxygen, the functional l-esidual capacity was
3,000 miUiliters; anatomical dead space was 150 ml, and alveolar ventilation was S50 ml per
breath. Each inspiration dilutes the nitrogen in the alveolar gas by ten percejjt T^e alveolar
nitrogen, therefore, on the first respiration deicreases from 80 to 72 percent. This continues
until alveolar nitrogen is washed out, and the lung contains only oxygen, carbon dioxide, and
wktm vapor. The puhnonary nitrogen may be washed out in a few minutes, but tissue and,
therefore, blood nitrogen are eliminated more slowly because the nitrogen miist diffuse from
the tissue to the blood, be transported to the hing, diffuse from blood to alveoli, aii4 then be
expelled from the lung on exhalation.
However, as tissue PN2 decreases, the diffusion rate also decreases since the gradient is
decreased. Jn addition, Mood supply to fatty tissue is rather low, and tissue perfusion rates are
correspondin^y low. Therefore, the denitrogenation curve is not a straight hne, as reference to
Figure 1-13 shows. Indeed, even after six hours of breathing lOQ percent oxygen to achieve the
optimal gradient, nitrogen still remains in the tissue in small quantities.
Since denitrogenation for long time periods is difficult in routine mihtary aviation, some
compromises must be, wsio. Figure 1-14 diows die relationship between pre exposure
denitrogenation periods and inddence of bends. Gener%: speaking,, two hours of denitrogena-
tion will give maximum protection against evolved-gas hypobarisnft, but One hour will provide a
considerable amount of protection. In the study, after a control period at ground level, subjeete
1-70
Physiology of Hi^t
were taken to 38,000 feet while breathing oxygen. At that altitude they performed five knee
bends every three minutes until the appearance of joint pains, presumably caused by
extravascular bubble formation.
850r
770
160 200 240 260 320 360
MINUTES
Figure 1-13. The rate at which nitrogen is eliminated from the body at sea level
when pure oxygen is breathed (Qamann, 1961).
The time period noted applies only to cantinuons breathing of oxygen from beginning
denitrogenatioii until exposure to low barometric pressure. If any "break" occurs during this
interval, and the subject breathes air for a short, period, the curves of Figure 1-13 and the
corresponding denitrogenation times are markedly affected.
A "break" 0f five Miimites after one hour m 100 percent oxygen would require another
25 miMm oSt oxygen to return to the same state of denitrogenation. SimUarly, after four hours
of denitrogenation, a break of five minutes would require two hours of additional oxygen
breathing to return to the prebreak state. Even so, bends have been reported after long periods
of denitrogenation.
In the current operational situation, purposeful denitrogenation is not used to protect
again^l evolved-gas hypobarism. One reason is that the pressure cabins and pressurization
systems are so reUable that a cabin altitude of 20,000 feet is rarely exceeded. In addition,
denitrogenation would require much time and the Utilization of equipment not now in
inventory.
1-71
20 30 40 50^ 60
DURATION OF EXPOSURE AT 38,000 FEET-MIN
Figure 1-14. Protection apinst deepinpressioa sickneas (Bfllings & Roth, 1964).
Aviators normaUy undergo some denitrogenation in the pre-taxi phase, although it is not
especiaUy planned that way. The period of oxygen breathing on the deck may be as long as
15 minutes, followed by thafr breathed during normal ascent to tjie operating altitude. The
ascent may add another 15 minutes, for a total of 30 minuter deMiti^OgeMoiiMfofe reaching
altitude. Reference to Figure 1-13 shows that about 49 percent of the nitrogen stores of the
body have been eliminated, and reference to Figure 1-14 shows that longer exposure at altitude
is possible before attaining the same probability of experiencing bends had a diluter-dem and
oxygen system been utilized. An important fact is that very few attacks of bends occur after the
litfelM3 hours of exp^fe.
At the altitude chamber of the Aviation Physiology Training Unit, denitrogenation is
routinely accomplished for 30 minutes before an altitude ran^aad-i? an e^eetive means of
preventing most cases of evolved-gas hypobarism.
mi
Physiology of Flight
Pressure Cabins. The simplest method of overcoming reduced-pressure effects is to provide
sea-level conditions in the cockpit. In actual practice, however, the provision of sea-level
conditions becomes impractical for a number of reasons.
Reciprocating engine aircraft use engine-driven compressors to provide pressurized air.
Aircraft with gas turbine engines normaUy use "bleed" air from one of the compressor stages of
the engine itself. The air supply must be capable of supplying an adequate volume of air during
reduced engine power settings such as those associated with descent. Pressurization capaeitf
thus must be adequate despite variations in power settings, decreased density of air at higher
altitudes, and leakage rates from the pressum cabin. The higher the differential required
between design cabin pressure and ambient pressure, the greater must be the capacity of the
pressurizing system, and the stronger (and heavier) the fuselage construction. The pressurization
of aircraft cabins represents an exceUent example of engineering tradeoff. A high differential
requires an aircraft structure wMch is physicaUy stronger and therefore heavier than that
required for a lower differential. The increased weight, in turn, decreases the payload of the
aircraft. Pressurization requires an expenditure of energy; therefore, the larger the differential,
the greater the power required to provide the desired pressure. The temperature increase which
occurs when air is compressed must also be considered. The higher the pressure, the higher the
temperature, and, thus, heat exchanger capacity must necessarily be larger. The higher the
pressure differential, the greater is file danger in the event of rapid decompression. FinaUy, cost
also is a factor.
Therefore, the pressurization schedule selected for a particular aircraft is typically a
compromise between physiological requirements, engineering capability, overall aircraft
performance, and cost.
Commercial and military air triwisport aireraft typically maintain a cabm pressure equivalent
of 8,000 feet of altitude (10.9 pa). Thus, flight to 40,000 feet (2.7 psi) is possible when an
8.5 psi differential, as used in civil air transport, is maintained. For this type of operation, cabin
pressurization to this level is entirely adequate. The slight loss in night vision capability which
might be experienced does not present any problem.
For military tactical aircraft, other considerations are involved in the selection of an
optimum pressurization system. The smaller cabin area of these aireraft means that loss of the
pressure seal through material failure or enemy action wiU create a-very rapid decompression.
In addition, rapid decompression may occur during the escape sequence for aircraft
equipped with ejection seats. In these aircraft, the overhead cailopy or escape hatch is
explosively removed during the initial ejection sequence. Some systems actually use the ejection
1-73
U,S. Naval Fli^t Surgeon's Manual
seat headrest as a hammer. During the upward movement of the seat, the headrest contacts and
fractures the plastic canopy, permitting the man/seat assembly to go through the canopy. Thus,
a rapid decompression is experienced.
In view of the above decompression possibilities, plusttefket tihat-noi-mal oxygen breathing
equipment is adequate up to 45,000 feet, and decompression sickness is unlikely at cabin
altitudes below 18,000 feet, lower pressure differentials are used in military combat aircraft.
liflSlfelwjftsweight peniaJtiiiS'are iftetured^ resulting in greater range and service ceiling.
GSIies (1965) sHinmariaies. the merits of high and low eabm pressure differentials as follows:
1. High Differential
3. Physiologicaliy more desttaJble jsabl^ conditions are insured.
b. Hie need for continued use of oxygen-breathing equipment is avoided*
e. Feeding and toilet arrangements are simplified.
d. Movingaboutwithintheaireraftinflipcf presents fewer difficulties.
2. Low Differential
a. The physical risks attendant upon sudden failure of pressurization are significantly
reduced.
b. Since normal cabin altitudes require the constant use of oxygen equipment,
occupants are in large measure akeady prepared to cope with the emergency of a
pressure failure. ^
c. The rapid failure of cabin pressurization may be accepted as an operational hazard,
and crews can safely be given practical training in dealing with it.
Figure 1-9 slhci^s a typical presMi&ation found in naval aircraft. From sea level to
8,000 feet no pressurization takes pfecsfe. Ffom 8,000 f^t to appteiiMStely 23,000^ feet is an
isobaric range in which pressure provides an 8,000 foot equivalent altitude.' Fftfm 23 ^ObO feet to
the service ceihng of the aircraft, a five psi differential pressure sdiedtfle is maintaiAedL
The air conditioning and pressurization system of pressurized cabin aircraft controls the
following:
1. Pressurization
2. Ventilation
3. Temperature
4. Humidiiy,
1-74
Physiology of Flight
The pressurization system consists of an air intake, a means of increasing the pressure of the
air, and control mechanisms which maintain the desired pressure. As previously mentioned, in
piston engine aircraft, air is obtained from ifttn sdr icoops, WMlfe "iie ^rb<^ ' for gas
turbine-powered aircraft is bleed air from one of the engine compressor Stages. For conventional
aircraft, the air enters a rotary engine-driven compressor and is distributed to the cabin. The
pressure differential is controlled by pressure sensors which in turn control the outflow of air
from the cabin. For practical purposes, the pressurization controls can be classified in two
categories. First is the t}'pe associated with transport aircraft in which the pressure control
aneroid senses cabin pressure and maintains a eori^t pressure, the '9,000 ^Bbf fe'abiA' fltitade
type. The second type senses both cabin and ambieift ^rfesstore s&d ccitttrols the cabin pressure
on the basis of a fixed pressure dSEferential. The five psi systems are found in most Navy tactical
aireritft. Figure 1-9 sViows a combination control with the first type maintaining isobaric cabin
pressure until 23,000 feet is reached, and the differential control taking over at higher altitudes.
Although pressurization is principally to provide proper air pressure, other factors are
important. High descent rates may produce severe barotrauma. In order to lessen this risk, some
pressurization systems provide for a reduced rate of pressure increase during high rates of
descent in the lower altitudes in which the rate of pressure increase is highest. For example,
when performing a jet penetration, the pilot may descend at 4,000 feet per minute. The
pressurization system, however, may be hmited to a 500-foot-per-minute rate of pressure
increase below 8,000 feet. Thus, upon descending from 8,0d0 feet to 4,000 feet (in one
minute), the cabin altitude will be 7,500 feet due to the tellbferate lag built into the
pressurization control device.
The pressurization system normally includes a cabin altimeter which permits the pdot to
observe his cabin altitude. Controls are also provided to release cabin pressure or in some cases
to select the cabin pressure differential. The latter capability permits the pilot to select a high
pressure differential during cruise portions of a flight, where the risk of loss of cabin pressure
integrity through enemy action is minwa^l, and ttJ gefett ft low pressure differential when in the
high-risk combat area, thereby lessening etSetm of 4.ri#i decompression.
Ventilation is provided, to some degree, by the pressurization control system which nor-
maUy regulates the amount of cabin leakage. Ths amount of idr flow required to ventilate a
cabin adequately has been recommended by McFarland (1953) as 35 to 40 cubic feet of fresh
air per minute per passenger. In any event, 15 to 20 cubic feet should be fresh rather than recir-
culated air. McFarland also suggests a velocity of air movement of 20 to 60 feet per minute when
heating is involved and 40 to 50 feet per minute when cooling of air is required. It is generaUy
agreed that a feeUng of stuffiness exists when air velocity falls below about 15 feet per minute.
1-75
U.S. Naval Flight Surgeon's Manual
Military nontransport aircraft normally provide some flexibility in ventilation control at
each crewmember station. Thus, foot ducts, seat cushion, head outlets, etc. can, in many cases,
be selected and controUed hj Jfc^f f at .©eeftpiit, qoiitp^lis ftYailabk fer boft ilie rate of flow of
air and the desiretj^e^perature, In most cases, terapereture is automaticaUy maintained at the
setting; selected.
Temperatures vary widely in the environments which one might encounter on the surface of
tiie earth. These variations are a factor of both geographic location (and elevation) and time of
year. Unfortunately, because &f M compilation of so-caUed «st«nd#l:4" tables, it is not
generally recognized that wide variations are also found at altitWtfe, ilgure 1-15 shows the
variations in environmental temperature which can be encountered at different altitudes in the
worldwide operation of aircraft. The center curve represent the values for temperature versus
altitude depicted in the standard altitude of Table 1-2.
Figure 1-15. Maximum and minimum atmos-
pheric temperatures encountered in the world-
wide operation of mtf^tsA at various altitudes
(Brown, 1965).
l-f6
Phytfblogy ofHi^t
A number of factors influence the temperature of the aircraft cabin. High-altitude flight is
frequently above any cloud formations with the aircraft exposed to direct solar radiation. The
transparent canopy and window materials permit the entrance of shortwave heat radiation,
which is then radiated about the cabin as longwave radiation to which the transparent materials
are opaque. This greenhouse effect, plus the absorption of solar radiation by the airframe itself,
causes an increase in cabin temperature. ■ • t t»i: ' • . - . , .
As the aircraft travels through the air, it tends to compress the air before it. While this effect
is negligible at low airspeeds, it becomes a factor at high airspeeds. This increase in pressure is
also attendant to an increase in temperature. The temperature increase is frequently termed
"ram rise" or simply "ram." Friction bet\^efen the^air and the aircraft also causes an increase in
temperature. Botk phenomena are termed collectively as "kinetic heating." Figure 1-16
indicates the rise in air temperature which can be expecfed at various airspeeds and at two air
temperatures. _
Figure 1-16. W^t oi airspeed ana enviroitfhentai fei^i*flat^ kfai^ifelseftii^
(Brown, 1965).
1-77
U.S. Nay^l jli^t Siii^n> Manual
As mentioned, the compressing of air perse causes an increase in temperature. At lower
altitudes, where air is more dense, the temperature rise is small, and air must enter a heat
exchanger to be warmed prior to being discharged into the cabin area. As altitude increases, the
compressing of the less dense air causes a large rise in temperature which creates a need to cool
the pressurized air prior to delivering it to the cabin. Table 1-18 shows the effect of compression
on the temperature of air and heating/cooling requirements while ascending to 45,000 feet and
majntafriiiig an 8,000-foot cabin altitude and a cabin temperature of 65^ F. It is assumed that
the aircraft climb true aitspe&d is 300 knots, that it has five occupants, f or j^ektbiie is Jttl Hir
supply of one pound per minute, and cabin surface is 200 stpiari feet. Ml© w# teit^fei^aiHre is
65° F, and conductance of the wall is 0.55 Btu's. >■<>■,- . •
.TaWel-ie
, V , , , Heating and Cooling Requirements of an Aircraft Cabin Kept at 65''r
I and Pressurized to 10.9 lb./in.2 (8,000 Feet) ^t All Altitudes
Plane
altitude,
feet ■
Cabin
altitude,
ieet
Atmo-
sphere
temper-
ature "F
Cabin
heat loss
Btu/hr
Required
temper-
ature of air
supply »F
Temper-
ature of
compressed
air "F
Supple-
mentary
heating
required
Bcu/hr
Cooline
required
Btu/hr
8, ooo
8, 000
+ 31
%, 600
76
+ V
3, 100
None
15, 000
8, 000
-9
5,700
119
65
3,900
None
18, 000
8, ocpo
-41
8, loo
100
3,700
None
35.331
8, 000
-67
10, JOO
184
H5
2,800
None
4o» 000
8, 000
-67
I O, li>Q
lio
Um^
1,700
45. o«j
8,000
-67
Id, Odd
179
333
Sons
11, 100
(From Bulletin I, 149, Decompression Sickness, Yaglou, CP., Division of Medical Sciencu,
National Academy of Sciences - National Research Council, Washington, D.C 1943 149 m
w reported in Broini,196S). . '
Absolute humidity, dew point, and ambient temperature decrease as altitude increases.
When the cold, diy, am4»fent air found at altitude is compressed, some increase in humidity
takes place. However, this is relatively insi^illil.' Table 1^9 shows the resulting relative
humidity for various cabin differential pressures, assumir^ a final air temperature of 65° Fand
the starting air at maximum absolute humidity.
From the table it is obvious that additional humidification is required if a comfortable level of
humidity (30 to 50 percent) is to be afforded passengers. However, military tactical aircraft rarely
provide any supplementary humidification. This presents no particular comfort problem since
tBttit>erature control is availifBfe iti i^dst eadh stalon, and various flight garments are available to
offset any chilling effects of low humidity. The drying effect of low humidity on oronasal passages
presents a chronic but not serious problem.
TaMe 1-19
Effect of Altitude and Gdrin Pressurization on the Relative Httmidity Within Aircraft
Aircraft
Ifeet)
4, ooo
5,000
6, 000
7. 000
8, 000
g, 000
lo, 000
15, 000
2^006
35,000
Maidmam
absolute
humidity of
atmosphere
0-9074
0-Q06
13-0055
0-0049
0-0043
0-0039
o-ooii
o-tioiz
0-00056
0-bo014
0-00006
o-oocxj6
o^tjooo€
Rdative humidity in aircraft cabin for various cabin differentials, and assuming a final temperature 65° F
No
pressurization
Cpasent)
z lb/in2
(percent)
3 Ib/in^
(percent)
4 lb/in2
(percent)
5 lb/in2
(percent)
6 ib/in=
(percent)
7 Ib/in^
(percent)
8 Ib/in-
(percent)
9 lb/io«
(percent)
48.5
41.8
3.6-4 ,
2.7. 6
-3 3
10. 4
9-45
3.96
1.58s
0.545
0. 108
0.085
0. 067
55-8
49.8
41.5
37-7
31.6
17-7
14.4
11.75
5.46
z. 17
0.79Z
0. 17
0. 147
0.1x9
40. 6
19.9
16. 4
iz. 85
6. oj
z. 46
0. 9Z
0. 101
0.178
0. 16
3Z.1
z8.s
14. 0
6.7
2-. 75
1. 04
0.143
O.XI
0. 191
15,1
7.3
3.04
1. 16
0. 163
0,341
Q. ZI3
16.3
7. 95
3.34
1. 19
0.1.95
0. 171
0-154
8.55
3.61
1.415
0. 316
0. 303
0. Z85
3.91
1-53
0.358
°-334
0.317
4.x
1.67
0. 388
0.365
o- 347
(Brown, 1965).
Rapid Decompression
When dealing with a pressurized cahin, one must consider the effects of a sudden loss of
pressure due to mechanical failure of the system, especially in the case of perforation of the
cabin walls, battle damage, or loss of the canopy. If the time characteristic (time to change to
new pressure) of the lungs and airways is greater than the time characteristic of the aircraft
cabin, a transient differential pressure buildup must occur within the lungs, as shown in
fipte 1-17. Although a review of studies (BiUMigi, 19^Sb)ih!0WS th4 mammdian lung may
rupture when distended by a differential pressure above about 80 mm Hg, the few instances in
which this has been done left the subjects apparently uninjured. This undoubtedly results from
the fact that the time characteristic of the lungs can vary considerably, depending on the phase
of respiration in which the decompression occurs.
<00( 1 1 I 1 1 1 1 1 1
TIME AFTEJ^ ^jp^dPRi^CWj^JWe
Figure 1-17. Sdbetnatic dia^am of origin of pressure differentials in the lungs
dnmg E^nd d^inpi«ie»on (fillings, 1973b).
In the event of rapid decompression, the following factors will govern the decompression
rate and l3se physiologic eHmts t ;
1. Cabin Volume - Other factora reittaS&g Cii^ a k^ec. space wiU take longer to
decompress than a smaller one.
2. Size of the Opening - The relationship between cross-sectional area of perforation and
the cabin volume will be the main factor determining decompression rate. The larger the
perforation, the more rapid is the decompression rate.
1-80
Physiology of Flight
3. Pressure Ratio (P Cabin/P ambient) - Hi^ larger iJie pressure ratio, Ae longer is the
decompression time. <»'! ' r.
4. ;fteS8ure Differential - The difference between ambient pressure and cabin pressure
influences the severity of the decompression but not the rate. The larger the pressure
change, the more severe is the decompression.
5. Flight Altitude - Apart from the rapid decompression itself, the flight altitude
determines the severity of the physiological effects on ibe bo4y after equilibrium has
been reached, particularly with reference to hypoxia and aeroembolism.
From study of the rapid decompressions which have actually occurred in flight, it appears
that the primary danger from decompression is the possibility of being blown through the
opening or being struck by flying debris. There is, as noted, soAMe pioS^ilitf of tf4MH»a froirithe
sudden expansion of gas within the body but only if thte glottis is fixed at the of
decompression, which is unhkely.
A method has been developed which may be useful in deciding the safety of pressure
systems relating to possible decompression. Two formulae are used:
Pc-0.91
RGE (theoretical) = q
(^ ) (^)
RGE (maximum) = 2.1 +
RGE = relative gas expansion ' "
A = total cross-sectional area (square inches) of openmg Oafgest^lexii^ass opeian|
is suggested for calculations)
Vc = cabin volume (cubic feet)
Pa = atmospheric pressure (psi) ,
Pc = cabin pressure (psi)
If RGE (theoretical) is greater than RGE (maximum), danger is present. If RGE (maximum) is
greater, the operating conditions may be considered safe.
1-81
U.S. Nayja!,f|i^t Surgeon's Manual
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Physiology of Fli^t
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1-84
Physiology of Flight
Maher, J.T., Cymerman, A., Reeves, J.T., Cruz, J.C., Denniston, J.C. & GroveriR.F. Acute mountain sicjaiess:
Increased severity in eucapnic hypoxia. Aviation, Space, and Environment^ ilfedunne, 19T5, 46, 82€-829.
McFailand, R*A. Human factors in air transportation. New York: McGraw-Hill, 1953,
Mclver, R.G. Management of bends arising daring space flight. Aerospace Medicine, 1968, 39, 1084-1086.
Mehmel, H.C., Duvelleray, M.A., & Laver, M. Response of coronary blood flow to pH-ind»ced changes in Hb-02
affinity. Journal of Applied Physiology, 1973, 35, 485-489.
Meijne, N.G. Decompression sickness and the cardiovascular system. In D.E. Busby (Ed.), Recent advances in
aerospace medicine. Proceedings of the 18th International Congress of Aviation and Space Medicine,
Amsterdam, 1969. Dordrecht, Holland: D. Reidel Publishing Co., 1970. Pp. 188-197.
Petty, C.A., & Bogeant, T.B. Effects of morphine, meperidine, fentanyl, and naloxone on Hb-02 dissociation
curve. Journal of I^armaBolt^ and Experimental '^erapeutics, 1974, 190, 176-179.
Phillip, R.B., Inwood, MJ., & Warren, B.A. Interactions between gas bubbles and components of the blood:
Implications in decompression sickness. Aerospace Medicine, 1972, 43 , 946-953.
Pittinger, C.B. Hyperbaric oxygenation. Springfield, HI.: Charles C. Thomas, 1966.
Roughton, F.J., & Severinghaus, J.W. An accurate determination of O2 dissociation curve of blood above 98.7%
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35, 861-868.
Samuelsson, R. Effects of severe systemic hypoxia on myocardial excitation. Journal of Scandinavian
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Scott, V. Anemia and airiine fli^t duties. Aviation, Space, and Environmental Medicine, 1975, 46, 830-835.
Topliff, E.D.L. Mechanism of lung damage in explosive decompression. .Aviation, Space, and Environmental
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1-85
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CHAPTER 2
ACCELERATION AND VIBRATION
Prolonged Accelerations ■ "
Impact Accelerations
Vibration
References
Prolonged Accelerations
Modern naval aviation requires pilots and aircrew to undergo exposure to a wide range of
accelerations and decelerations. So exposed, the body may exhibit many changes, ranging from
a mild increase in fatigue to complete cifCiiIatory eoHapse* Su«h changes ©Wtjualy «J!6gb.4it#
performance and survivability of the aviator. The flJ^t cha-acteristics of modern naval aireraftv
such as the F-14 md the F-18, are such that the limiting factor to acceleration stress has become
the man rather than the machine. An understanding of acceleration forces and the human
response to them is vital to the Fhght Surgeon and the aviator. Equally important is a
knowledge of avenues available now and in the foreseen future to increase human tolerance to
these stresses. Ignorance in these areas can lead to otherwise avoidable accidents.
ClaeiMteation md Tefvaotkidlo^ "
Aifcileralioji ticcurs when tihe velocity or direclSbn of motioii of a body changes. In
aerospace medicine, three types of acceleration forces are generally described: linear
acceleration, radial acceleration, and angular acceleration. Most forces encountered in actual
flight are combinations of the three.
Lmm acceleration occurs when the velocity of a body is varied without a Gorresporiding
change in its direction of motion. In naval aviation, this is commonly encountered in catapult
launetun^, arrested Iaiii®3ftgs, ejections, cr^h landings, and ditchings.
Radial acceleration occurs when the direction of motion of a body is changed with the
velocity remaining constant. Common usage in aerospace medicine Arsms a fettrfction between
radial accfeltefAtiott, in "wMch the axis of rotation is external to tKe pilot's Bod:^ tttid aa^Klar
acceleration, in which the axii Sf i-otatittn passes through or near the pilot. The former might be
encountered in any change of aircraft attitude or heading, while the latter would be expected in
2-1
U.S. Naval Flight Surgeon's Manual
such isituations as minimum radius turns and spins. The effects of angular acceleration on pilot
disorientation are discussed elsewhere in this manual.
Two sets of terminology are commonly used when referring to the direction of acceleration
forces. One refers to the direction of the actual acceleration vector, while the other refers to the
direction of the associated inertial force vector. These force vectors are always directly opposed
to one another. For a detailed explanation of this terminology, see Table 2-1. Measurement of
these forces is in terms of G, or multiples of the acceleration due to gravity (32 ft/sec^ or
981 cm/sec^).
Effects on the Body
Blood and tissue fluid are the most mobile tissues in the body; thus, hemodynamic shifts are
leading causes of physical disruptions under G4oads. In general, the more closely the inertial
vector parallels the major blood vessels passing along the spine, the stronger are the alterations
in hemodynamics (Vasil'yev & Kotovskaya, 1975). Transverse accelerations produce
hemodynamic changes which are primarily regional. Following is a discussion of the physiologic
effects of acceleration on the body, system by system.
Cardiovascular System. Cardiovascular changes are greatest under ±G^ stress. +0^, or
eyeballs-down acceleration, causes relative displacement of the blood mass toward the vessels of
the abdominal cavity and the lower extremities, resulting in a relative increase in blood pressure
below the heart and a decrease above the heart. This can lead to ischemia of the brain and sense
organs, visual disturbances, and possible loss of consciousness. These blood pressure changes
affect the carotid sinus and other angioreceptors, and compensatory mechanisms come into play
to increase peripheral resistance. A finite lag in the onset of these mechanisms may explain the
occurrence of visual disturbances or loss of consciousness. On the other hand, the difference
between arterial and venous pressure in the head has been shown to maintain partial cerebral
blood flow by a siphoning effect, even when arterial pressure has dropped to zero {VasU'yev &
Kotovskaya, 1975). At any rate, a definite correlation has been established between visual loss
and impending syncope.
Animal and human studies have shown the occurrence of various cardiac arrhythmias during
high sustained +Gj, and have related these changes to myocardial ischemia (Erickson, Sandler, &
Stone, 1976; Forhni & ForUni, 1976; Gillingham & Winter, 1976). For the most part, these have
been mild and short-lived. There are conflicting reports regarding the duration of cardiac
compromise, in general, following high sustained -KJ^ (Peterson, Bishop, & Erickson, 1975;
Strom, Wilen, Bush, Zalesky, & Baumgardner, 1976), and more work needs to be done.
Table 2-1
Physiolo^pl Acceleration Systems*
^ — ' ■■
System 2
System S*"*'
Sjstem 5
Verbal d^nidon
[1]
Pictorial
deMriptipn
[21
t
Descriptive
[31
ular de-
scrip lioB
[4]
K
AGARD
ayrn-
bols"
15i
r
Heart dia-
placeraenl
[6]
\y
FCftwAr-r. j/
»■ DACRTAUD*.
-ff'- 1
HEADWARD
NEOATIV^E D -^.^
SOPWEG 1/ PHONE a
sr
[8J
[91
[101
I
Linear forces or accelerations
AfoFcc applied to the poa terio r
pMt of the trunk* acting /or-
ward with respect to the subject
and perpendicular to the mean
spine prodiuxsa forward accel- '
eration
Forward
acceleration
or
forward acting
foTCo
Ejeballs
in
Moves
toward
back
Forward
acceleration
Traaaverne A-P C
Supine G
Cheat to back G
Sternum-
ward
Surgs
A fores applied to iKe anterior
part of the trunk, ,aaff«^ feocAr-
ward wiih i^^^eei id 't%e subject
and perpendicufer to the mean
spine pradttces a hitcktoard ac-
^^^^
Backward
acceleration
or
backward acting
force
Eyeballs
out
Moves
toward
front
Backward
acceleration
Transverse P-A G
Prone G
Back to chest G
SpinC'
ward
A forc*i applied to the left s,\\r-
face of the siibjeci'^ body,
acting in a rigkttottrd diret.tiort
and essentially perpendicular
to the sutject^a mean spine
produces a riglttiettrd accf^tcra-
tion
Rightward
acceleration
or
rightward
acting forc9
Eyeball!)
left
Moves
toward
left
Right lateral
acceleration
Left lateral G
Left sw*y
(See footnotes at end of table.)
Table 2-1 (Continued)
Physiological Acceleration Systems*
System 1
System 2
System 4
System 5
Verb*! deGnition
tl]
Pictoriat
deacriptiOQ
(21
Descriptive
terms
[31
Vernae-
acription
[41
\y
r
m
KECATIVE C
SnPME 0 i/ PHONE a
k-r THANSVEHSE/fc TBANSVERSE
^ pcwnvEa
[8]
19)
[lOJ
AGARD
sym*
hols'"
[5]
Heart diS'
placement
(6)
Line
ar forces or accelerations
A /brce applied to ihe right sur-
face of the subjecfa body, act-
ing in a leftward direction and
essentialljr perpendicular to
the subject's mean apinc pro-
duces a leftward acceleraiion
f
Leftward
acceleration
or
leftward acting
force
Eyeballs
right
-c.
MoTes
toward
right
Left lateral
acceleration
Right lateral G
Right
away
j4/0rce applied to ihe buttocks,
thigha, and/or feet, actingia a
headtoard dirieti&n with respect
to the subject and essentiallj
parallel to the gubject^s mean
spine produces 0 h^adward ac-
celereuion
Headward
acceleration
or
headward acting
force
EyebalU
down
+ G.
MoTea
toward
feet
Headward
acceleration
Poaitira C
Head,
ward
A force applied to tlie ahoul'
dersf thighs, and feet of a
seated human acting in a tail-
ward direction with respect to
the subject and eaaeDtiiilly par-
allel to the Bubject^s mean
apine produces a tailivard ac-
celeration
Tailwatd
acceleration
or
lailward acting
force
Ejeballs
up
- G,
Moves
toward
head
Footword
acceleration
Negatire G
Tailwaxd
Hear*
Table 2-1 (Continued)
Physiological Acceleration Systems^
Onciihtorf forces or iceeleistian
I
Forces thai alternate in direc-
tion and produce alternately
forward and backward motion
of the subject, and that act
essentially per])eiidicular to
the spine, produflSj5»((»<ff*«i*
accderation
force* that alternate in direc-
tion and produce alternately
aide to side motion of the sub-
ject, and that act essentiatly
perpendicular to the spine,
produce tide to tide acederation
Forces that aliernaic in dirco-
tioo wad jiroduco alternately
tiieaif to {hi motion of the sub-
jccl, and tlial Ml csseniially
parallel to llie spine, produce
henii In tail ncceleriuian
Front-to-baot
oscillating
force
or
acceleration
Side-to-sida
oscitlatiog
force
or
■cceleratian
Mead-lo-iail
oscillating
force
or
acceleration
Oscillates
fote-and-
aft within
thorax
OseillatfM
side- to-
side vithin
tboru
OacilUtcs
h ead-to -
tail within
thorax
Angular inomeata or acceleration
A ralalionnl mnmeat or caiiple
that projiu'i-s a hrad Uft mi>-
tion of the subject thai Wl'S
esseiitinlly in tlio froiUiil
tshoulder-lo-aliouldf^i") plane
produces a head left <-(ir(u..'ii-.-(-
ing angular acceleration
Head left
cartwheeling
moment
or
acceleration
- Rx
Top tilts
toward
fight
Bboulder
A rotational mamtnt or couple
that produces a head riftht mo-
tion of thr subjc-ct that lies
esfcritiallr in tiie frorilnl
(sliouLIer'Tn-^iimihlcr) plaiu'
pri^diirc.'* a h^nd riaht cnrt-
u-heeling angular acrclcralion
Head right
cartwheeling
mom*-ni
or
acceleration
-1- R.
Top tilta
towarfJ lefl
alioulder
(Sec footnotes at end of table.)
Table 2-1 (Continued)
Physiological Acceleration Systems*
S)
Stem 1
1 —
System 2
System 3*'- '
Syatem 4
Verbal definidon
Pictorial
description
Descriptive
Vernac-
ular de-
acriptioD
-^"^
•J
0" »■
, tr ''
■f- ' '
HEGATIVE C
SUPINE 0 |/ PRONE a
A.-P TBANSVERSE/t p-A THANSVERSE
POSTTIVE Q
V
[81
[I]
(21
[31
[41
AGARD
hols''
[5]
Heart dia-
placement
[61
[91
[10!
Angular momentH or acceleration
—continued
A rotational momerit or couple
that produces a head-forward
feet backward tumbling motion
of the gubjecl that lies egaen-
lially in the saggital plane pro-
duces s forward someraautting
anguJar acceleration
Forward
som,erBaulting
moment
or
acceleration
- Ry
Top (ilta
toward
spine
—
—
—
■
A rotational momeni or couple
lhal produces a head'hackward
feet' forward tumbling motinn
of the subject that lieg csaen-
tialty in the aaggital plaoe pro-
duces a backward somersaulting
angular acceleration
Backward
aomerBauItiDg
moment
or
acceleration
+ Rj-
Top tilts
toward
aternurii
—
—
—
—
A rotational moment or couple
ibat producea a right-turn mo-
tion of the guhject about the
apine in the saggiial plane pro-
duces a rlgfit twisting angular
acceleration
Right
twinting
tUDment
or
acceleration
+ R.
Twists
toward
aubjecE'a
left
—
—
A rotational mon%f;nt or couple
that products a left-tarn motion
of the Bubjflcl about the apine
in the Bapf^ital plane produces
a Iffi twisting ongcilar accelera-
Left
tvristiag
moment
or
acceleration
- R.
Twigis
toward
auhjcci's
riflht
Ubulalcd in column 3 and (he "eyeballs" vernacular temu ire
are iBtPd in culuinn 5. The reaction and motion of the heart wi
•lifted iTr^lnrnfi ¥L„„K "-^ ^ ""^ l?>cb.T^i in cokimn 2. The descriptive terms to he used in discussions are
{U.S. yaval Flight Surgeon'i Manual, 1968)
Acceleration and Vibration
Several studies (Burton & MacKenzie, 1976; Lindsey, Dowell, Sordahl, Erickson, & Stone,
1976; MacKenzie, Burton, & Butcher, 1976) have found pathological evIdSMde- o|
subendocardial hemorrhage and Stress cardiomyopathy in miniature swine following exposure
to high BUlt^ed +0^. These changes were located most often near and in the Purkinje fibers
and were associated with tachycardia around 200 beats per minute (bpm) as well as with a
positive inotropic effect. Sandler, Carlson, McCutcheon, and Bums (1976) suggested relative
myocardial ischemia as the most hkely etiologic factor. This would seem reasonable, since the
subendocardium is the least well perfused area of the myocardium, making it most susceptible
to Ischemia. The implication of these findings for man remains to be i^e^ennined.
Eastward or eyeballs-up acceleration, -G^, causes blood displacement toward the head and
a relative rise in blood pressure above the level of the heart. The rise in carotid artery blood
pressure causes stimulation of the carotid sinus, leading to vagally induced cardiac arrhytiimias,
including sinus brad.ycardia and sinus arrest with junctional rhythm (Chrislf , 1971;
Kirkland, & Sneider, W^). See Eigure 2-1.
f
-
J
\
— >
-1 G
1-
-
\
.A
%
:1
A
1=
V
—2 G'
X
=1
-
Figure 2-1. Electtocsidiographic monitor during n^ptive acceleration; +1 G: Subject is in upright seat
recovering from a -1.5 G exposure. Rhythm is smtts i»ilh a P-R iBteWal di OM s. -*.l G: Subject is inverted in
centrifuge cab. Absence of P wave for two or three complexes with apparent jijnc^Oiid In«cham8^
recovery of sinus mechanism, -2 G; Subject remains inverted and arm of C^ritriftigeiffmO^n'g'fd ifeBVteV— 2 G.
The rhythm is slow and irregular with an apparent junctional mechanism. -1 G: Centrifuge is stopped with
subject remaining inverted in cab. Bradycardia persists. (Kennealy, Kirkland, & Sneider, 1976). Published by
permission of Avia^n, Space, and Environmentul Medicine.
2-7
U.S. Naval Flight Surgeon's Manual
Forward or eyeballs-in acceleration, +G^, produces cardiac arrhythmias similar to those
produced by -G^, and presumably for similar reasons, although physical trauma of the spine
and sternum could also be involved. At +10 G,,, cardiac output is decreased due to increased
peripheral resistance, particularly in the vascular lumina of the abdomen and muscles (Vasiryev
& Kotovskaya, 1975).
_ Respiratory System. Acceleration forces in all planes cause local A-V shunting and other
V/Q (ventilation/perfusion) abnormalities within the lungs and resultant deterioration in gas
exchange. The decreased arterial blood oxygenation is never as severe as for hypoxic hypoxia,
but, when added to local insufficiencies in blood supply under the acceleration environment, it
is an important contributor to tissue hypoxia. Partial compensation for this might be attained
by breathing 100 percent oxygen, but this theoretical benefit could be counteracted by oxygen
atalectasis. Under stress, the factor of mechanical compression of the thorax is added,
causing decreased pulmonary reserve and reduced ventilatory effectiveness.
Vision. When acceleration stress is primarily in the plane, visual disruptions are reliable
indicators of impending syncope due to decrease in cerebral blood flow. As the resultant
acceleration vector tends toward +G^, visual disturbances tend to indicate impairment of retinal
circulation alone. Visual symptoms usually consist of constriction of the visual fields, hmitation
of voluntary eye movement, poor light sensitivity, impairment of detailed vision, and finally
blackout. They are explained by a decrease in blood pressure in the central retinal artery to
below 22 to 23 mm Hg, the level of intraocular pressure.
Central Nervous System. G^ and forces alike cause decreased perception and increased
reaction times to auditory and visual signals. The most Ukely cause is increasing hypoxia, but
some authors have implicated increased afferent input from deformed organs and tissues
(Cananau, Groza, Albu, Dragomir, Petrascu, & Zaharia, 1975; Vasil'yev & Kotovskaya, 1975).
Whatever the cause, these functional CNS disturbances effectively reduce man's working
capacity.
Renal System. Aviators exposed to as much as +6 G^ have sometimes developed microscopic
hematuria and granular casts in the urine. The etiology is believed to be increased glomerular
capillary permeability due to interrupted blood flow. Loads of up to +10 G^ have caused
diuresis attributed to hemodynamically induced increases in glomerular filtration rate.
Work Capacity and Man's Resistance to Acceleration
Estimations of man's tolerance to various acceleration stresses can best be made by
following the criteria laid out in Table 2-2. Because Gy stresses have not been adequately
studied, they are not included.
2-8
( I
Acceleration andTihration
Criteria for Estimating Human Tolerance Limits
to Acceleration Stress
Direction
of Stress
Signs of Tolerance Limit
Visual Grayout/Bladcoat
Headache, UKA^imatfon, "'Rftd-oMf"
Relative Bradycardia, Visual Loss, Dyspnea
Decreased Visual Activity ("fogging")
Chest Pain (related to restraint system)
(Adapted from Vasil'yev & Kotovskaya, 1975).
In general, man is least resistant to the effects of -G^ and most resistant to +0^, as shown
in Figure 2-2. From this, it also becomes apparent that duration of exposure is quite significant.
Several other factors influence man's tolerance to acceleration, including training, physical
fitness, and adaptation. Tensing of the musculature of the loWer BxtfeM&s, abfliJitli^ Ml
shoulder girdle can tecreaae the tfereahold of blackout Bf as iiii« as +2G^. TOe'Mil itttoeuVer
combines muscle terision with forced expiraion B0m a partially closed glottis, and it can
iftcreiife*he1!hce|liold by an additional 0.5 G^. Cotiveraely, hypoxia, dehydration, medication,
and high ambient temperatates att reduce acceleration tolerance.
80-1
60-
C3 40-
o
1 10-
^ 6 -
S 4-
u
< 2-
1
.01
■T — TTTT
.02 .04 .1
I 1 1
.2 .4 .6
Time,
T
1
min
t I 'I 1 1- — I 1
2 4 6 10 20 40
Figure 2-2. Man's resistance to the effects of
acceleration in various directions. Mean data on
(heaii to pelvis). -Ga (pelvis to head). -Gx chest to
back). -Gx Qtask to chest) directioii of inertial
forces). (Vasilyev, & Kotovskaya, 1975).
Work capacity, in addition to leing affected by the factors aescr^d abiwe, is also
inflwenced by mechanical forces which inhibit certain muscle groups. For example, at +8 G^.tt
2-9
U.S. Naval Flight Surgeon's Maniuil
is impossible to raise the body or extremities, but carpal joint motion is possible up to about
+25 G^. Training and proper design of the man-machine interface can help overcome such
problems.
Mechanical Methods for Increasing Resistance to Acceleration
Several devices for increasing man's resistance to acceleration are currently in use or under
investigation. The anti-G suit, by providing compression to the abdomen and legs, may improve
tolerance by as much as +2 G^. It is required apparel for aU naval aviators on flights where high
G-forces might be expected. Much work is now being done to evaluate special seats, such as the
pelvis- and leg-elevating (PALE) seat, designed to maintain the aviator in an optimal position
with respect to the acceleration vector (von Beckh, Voge, & Bowman, 1976). Such seats hold
promise for the future.
Impact Accelerations
Impact, an acceleration with a pulse duration of not more than one second, may be
encountered in normal as well as emergency phases of naval aviation. The Flight Surgeon
involved in accident investigation wiU often find it necessary to determine the potential
survivabiUty of a particular crash situation. Such determinations are predicated on a knowledge
of actual human tolerance to impact. Much impact research has been conducted with regard to
automotive and aviation crashes, but many questions remain unanswered. The following is an
attempt to present useful information on which the operational Flight Surgeon might build.
Physiologic and Pathologic Effects of Impact
Direct injury to body tissues occurs when the tissues' mechanical stress Kmits are exceeded.
Unlike prolonged accelerations, impact accelerations are not accompanied by significant shifts
in blood volume; the duration of exposure is too short. Impact injuries result from a more direct
response of the body and its organs. In other words, with impact accelerations man responds
like porcelain, but he responds to prolonged accelerations like a hydraulic system.
Impact-related injuries vary from the subceUular level, escaping detection, to major trauma.
Head injuries, usually resulting from heavy blows to the head, are the most common causes
of crash fatalities. Cadaver studies have shown frontal bone load limits of 180 G over
0.002 seconds or 57 G over 0.02 seconds, when struck with a 2-inch diameter hammer surface
(Lewis, 1974).
Von Gierke and Brinkley (1975) cited data from 317 case histories involving head injury
which indicated that the severity of head injuries depends largely on the development of basilar
2-10
Acceleration and Vibration
skuU fractures and consequent involvement of the adjacent intracranial structures. Such injuries
almost invariably result if the impact velocity is greater than 5.0 m/sec. Frontal impacts tend to
be less severe clinically than temporal or occipital impacts. Gmtei than 60 G appUed frontaUy
will cjtuse concussion injpy.
Spinal impact associated with ejection may result in vertebral compression fractures. The
most common fracture sites are T-12 and L-1, although other sites may be involved due to poor
body position (Rotondo, 1975). The erect or hyperextended posture is ideal for ejections, but
during normal operations, pilots are usually in a flexed position.
-G^ impact has not been weU studied, but the speculation has been that intracranial
hemorrhage would be the Umiting factor. This has not been weU supported, however, by animal
studies completed as of this writing.
In a weU-supported and restirained individual, +0^^ ^pact causes various degrees of shock,
the main Umiting fSetO*: Bradycardia due to vagal activity has been observed. Som6 evidence of
Inspiratory damage hfts iflso been found (von Gierke & Brinkley, 1975). Contrary to the general
rule for impact, -G^ or eyeballs-out impact may lead to increased hydrostatic pressure m the
central retinal artery, causing conjunctivitis and retinal symptoms, such as scotomata (Lewis,
1974- von Gierke & Brinkley, 1975). Where a lap belt provides the only restiaint, -G^ impact
can kad to a ruptin^dm^. t^B&M iinpet (iGy)V«iou# ht* studied, can Ifead to
cardiovascular shock, Whole-feky^iiniiatet tolerance Htoits af6 outHtifeid in Table 2-3.
Table 2-3
Human Whole-Body Impact Tolerance Limits,
Based on 250 G/sec Onset Rate
Dir^tion
of Impact
Load Limit Over Time
A-
20 G over 0.1 second
15 Cover 0.1 second
83 G over 0.04 second
-G^ (full restraint)
45 G over 0.1 second
25 G over 0.2 second
-Gj, (lap belt)
13 G over 0.002 second (muscle strain)
27 G over 0.002 second (ruptured bladder)
1 9 G over 0.1 second
(Lewis, 1974).
2-11
U.S. Naval Flight Surgeon's Manual
Vibration
Vibration has commonly been considered more of an engineering problem than a medical
one. It is, however, a commonplace problem in the world of naval aviation and one with
far-reaching implications for the aviator's personal comfort, health, and performance. Thus, it is
imperative that the operational FHght Surgeon have a working knowledge of vibration and its
effects on man.
Definitions and Terminology
In everyday terms, vibration means shaking. In physical terms, it is a series of velocity
reversals, implying both displacement and acceleration/deceleration. It is described in terms of
its frequency, ampUtude, anatomical direction with regard to the body, and duration.
Frequency is usuaUy expressed in terms of cycles per second or hertz (Hz). Amplitude, the
extent of oscillation, is measured in meters or smaller metric units. The intensity, an extension
of the amphtude, is described in terms of its acceleration component, expressed in G. Complex
vibrations are often described in terms of the root-mean-square (RMS) intensity, a time-averaged
value. The output of many electronic instruments for vibration measurement is proportional to
the RMS. For more information see von Gierke, Nixon, and Guignard (1975).
There are four different types of vibration. Sinusoidal or simple harmonic vibration is
composed of a single frequency. When two or more sinusoidal vibrations are added together, a
compound harmonic vibration results. When the vibration is totally kregular and unpredictable,
it is termed a random vibration. Finally, harmonic vibrations can be added to random ones'
Graphic examples of these vibrations are pictured in Figure 2-3.
Resonance
Any vibratmg system has one or more characteristic frequencies at which forced vibration
will eUcit maximum or amplification response. The system is said to resonate at that frequency.
The amount of amplification at resonance is inversely related to the amount of damping, the
process opposing vibration, within the system.
The human body can be thought of as a complex vibrating system, with a number of
subsystems displaying different resonance characteristics. Such a system is illustrated in
Figure 2-4.
Sources of Vibration in Naval Aviation
The sources of vibration in naval aviation are myriad. Listed here are some of the principal
ones, taken from von Gierke and Clarke (1971).
2-12
Acceleration and Vibration
Vibrations
(a) Sinusoidal
(simple harmonic)
Spectra
■'11
■D
3
0
Time
(b) Compound harmonic
E 0
o
a.
F Frequency
±1
(c) Random ("white"]i
Frequency
a
■a
(dl Random + discrete frequencies
Frequency
Frequency
Figure 2-3. Diagram of waveforms and idealized power
spectra of typical varieties of vibration
(vonGierke, Nixon, & Guignard, 1975).
t 1 .( 1
Eyeball, Intraocular
structures (? 30-90 Hzl
Shoulder
girdle
|4-S Hz)
Chest wall
(ca 60 Hz)
Afedetnifial
mass (4-8 Hz)
Legs
(variable from
ca 2 Hz with
knees flexing
to over 20 Hz
Head (axldl mod;e)
{ca m Hz)
Spinal
column
(axial
mode)
(10-12 nn
Seated person
vytth rigid postuiej |l Standing person
Figure 24, Mechanical model (diagrammatic) of seated
and standing man
i (vonGierke, Nixon, & Guignaid, 1975).
2-13
U.S. Naval Flight Surgeon's Manual
o
Ejection. Once free of the rails, an ejection seat system seeks a stable configuration in the
airstream. This normally sets up an oscillation around the center of the seat-man system in the
range of 3 to 10 Hz and with a magnitude of 10° to 30«. These vibrations normally damp out
rather quickly, but the relatively large oscillations impose considerable threat of flail injury,
especially when combined with high aircraft speeds.
Low-Altitude, High-Speed Flight. Many current military missions include low-altitude,
high-speed flight in an attempt to avoid radar detection. Gust effects in such flights can
introduce complicated vibrations in five degrees of freedom, ranging from about 1 to 10 Hz.
This can present cUnical problems in the areas of vision, speech, respiratory ^ort, and
musculoskeletal stress not unlike a high-speed jeep ride over an open field.
Terrain Following. In order to fly in the low-level, high-speed profUe, many modern aircraft
have systems which allow flight close to the contour of the terrain. Such systems, whether
manual or automatic, can induce vibration spectra between 0.01 Hz and 0.1 Hz. This is in
addition to the gust response and can add the chnical problem of motion sickness.
Storm and Clear Air Turbulence. Storms and clear air turbulence impart vibration spectra
which are similar to low-altitude, high-speed flight. These vibrations are generally in the very
low frequency range, but clear air turbulence can occasionally be of such high frequency and (^^
intensity as to preclude control of an aircraft.
Helicopter Vibrations. Vibrations are perhaps of greater importance in helicopters than in
any other type of naval aircraft. These vibrations arise from mechanical and atmospheric
sources, although the atmospheric conditions are not as important as in fixed-wing aircraft due
to the lower airspeeds. Vibrations in the 3 to 12 Hz range are induced by the main rotor blades,
the actual frequency being related to the number of blades. Tail rotors produce higher
frequency vibrations, in the range of 20 to 25 Hz. Vibrations produced by the transmission are
less well defined. These generally low-amphtude vibrations have clinical significance by virtue of
the prolonged exposures involved, where physical fatigue results from continuous bracing.
Ill-defined musculoskeletal complaints, such as neck and back pain, appear with increased
frequency in the rotary -wing community.
V/STOL Aircraft. V/STOL aircraft in low hover appear to exhibit low-frequency range
vibrations similar to those found with helicopters. Their significance, however, seems to he more
in their effect on the pilot's response time than in any purely clinical effect.
U
2-14
Mc^at&^m md Vibratioii
Effects of Vibf slioii on the Body
■' A riiiri^lf df factors modify the effects of vibration on humans, inchiding tissue resonance,
duration of exposure, individual variations, and other simultaneous environmental stresses. For
example, acceleration increases the body's rigidity, reducing its shock-absorbing properties and
increasing the transmission of vibration energy to' fte orgto'(AM^6t; i5%dov,
Verigo, & Svlrezhev, 1975). The effects of viWation oh man are determined by the fffeq^eAcy
ranges involved.
Effects at less than 2 Hz. Vibrations in the frequency range of 0.1 to 0.7 Hz most often
produce motion sickness in man. Vibrations of 1 to 2 Hz are generaUy associated with increases
in pulmonary ventilation, heart rate, and sweat production ifcoveflhat lew! eontdwdftO^
for any other stress pres^I^i \ >f>viv
Effects from 2 to 12 Hz. Tolerance in this frequency range is usually limited by substernal
or subcostal chest pain, with thresholds at approximately 1 to 2 G, and 2 to 3 G,,. The etiology
of the pain is the same for both axes of vibration: Displacement of the abdominal and thoracic
viscera induces stretching of the chest waU, with torsion at the s&ste^^»«|M^t0«©f A©
ribs. Dyspnea is the secon4,«w«sefnMQo^sy3»pt^ ia l&ts fia»ge,.»ppamRfl^.w«i iie same
emm. SS^ pstob^Cftpfa^lM*^ produced by^mtons around
two axes at aceeleration awpttudes abtjve 0.S 0 in tJie range of 1 to 10 Hz.
Cardiovascular effects are maximized in G^±g^ {i.e., a G^ acceleration environment with
interposing ±g vibration) at 3 to 6 Hz and in G^±g^ at 6.to 10 Ha. Ito Aw|iS..^mt^
increases in heart rate, arteMbk«i|a^^t&, central wnta pTessum, aMdt6«i««otiif.ut; these
a^uaccompanied by a cifm^i^^^^^^^ ^ periphetttl. f^iteU' 'These changes all
resettible nonspecific exercise responses.
Abdominal discomfort and testicular pain are common complaints due to stretohinis^^
yiscera and force apphed to the spermatic cord, respectively.
• --r . :. t.....< . - J
The headache commonly aSSodated :*mteqWeW rSPge has several explanations. In a
Q te, enmonwent* the mechanical forces are not well attenuated by the skeletal system. In a
g"*^ environment, the head is forced out of phase with the headrest and repeatedly impacts
agdn^t it. G^±gy causes the same problem, only more so; it adds strain, spasm, and soreness of
the neck to the symptom complex.
245
U.S. Naval Flight Surgeon's Manual
Finally, bloody stools, transient albuminuria, and transient hematuria are occasionally seen
m helicopter pUots flying heavy schedules, and they are presumed due to vibration. These
changes usually disappear after a few days rest.
Effects above 12 Hz. In these frequencies, there is more concern about effects on
performance (vision, speech, fatigue) than about injuries.
Effects of Vibration on Performance
Vibration can greatly affect performance by inducing visual decrements. Frequencies below
2 Hz have little effect, but between 2 and 12 Hz, relatively large displacements of the body with
respect to a given point on the instrument panel contribute to increasing visual impairment The
frequency ranges of 25 to 40 Hz and 60 to 90 Hz, however, lead to the greatest visual
mipairment due to the resonance of the head and eyeballs respectively (von Gierke & Clarke
1971). '
Performance can also be modified by vibratory effects on speech. Pitch is increased due to
generalized muscle tension during exposure. Single-word inteUigibility is decreased as a direct
function of vibration magnitude and frequency. Speech is least understandable with G ±g in
the same low frequencies that induce resonance of the thoraco-abdominal viscera.' These
problems underscore the importance of standard phraseology in naval aviation.
Very low -frequency, high-ampUtude vibrations often cause pUots to postpone flight
corrections until after the short surge of vibration is past. This could be an important
contributor to pUot-induced aircraft oscillations. Vibrations in the 2 to 12 Hz range cause
involuntary movement of the extremities, which, while not forcing control errors, may hinder
fine knob adjustment and writing.
Pathologic Effects of Vibrations
Animal experiments indicate that acute human injury from exposure to high levels of
whole-body vibration should resemble impact injuries from accelerations of comparable
magnitude and direction. Chronic occupational exposure to vibrational stress has been
impKcated in a number of disease processes, including Raynaud's phenomena, neuritis
decalcification and cysts of the carpi and long bones of the forearm, cutaneous scleroderma,
osteoarthritis, Dupuytren's contracture, bursitis, tenosynovitis, amyotropic lateral sclerosis,
carpal tunnel syndrome, Keinbock's disease, and periodontal disease (HaskeU, 1975; Strandness'
1974; Wasserman, 1976; Williams, 1975). In most of these cases, the role of vibration has not
been firmly established, and much work remains to be done in the area.
2-16
AcceleratioH and Vibration
Vibration Exposure Standards
The International Organization for Standardization (ISO) iias formed recommendations for
whole-body vibration exposure standards. A number of countries, including the United States,
are currently in the process of adopting these or similar standards. The ISO recommendations
are summarized in Figures 2-5 and 2-6. These standards are necessarily subject to change. They
are certain to come under much scrutiny, and refinement is inevitable.
The frequency function
Vibration
— — a;f,ay, Vibration
10.0-1
I 1 T — T T- — I n
1 2 4 8 16 31.5 6380
Frequency, Hz
Third-octave band center frequency, Hz
Figure 2-5. Proposed ISO "Fatigue-decreased proficiency"
boundaries (the frequency function)
(vonGierke, Nixon, & Giiignffid, 1975).
Protection Against Vibratieil
Pi-otective measures against vifcraHon M into t!iree general categories: control at tJie
source, control of transmission, and attempts to minimize effects on the man.
Control at the source is primarily a problem of engineering, and it wiU not be discussed
further in this chapter.
2-17
U.S. Naval Hight Surgeon's Manual
The exposure time function
cn
100-1
E
31.5-
c
10.0-
q
CO
3,15-
_®
(0
u
1.0-
u
to
CO
0.1-
1-2 Hz
n — I — r-
4 8 16
min
1
T-
2
Exposure time
-| — r
4 8
h
1
24
Figure 2-6. Proposed ISO "Fatigue-decreased proficiency'
boundaries (the time function)
(vonGierke, Nixon, & Guignard, 1975).
Control of transmission can be attempted in several ways. The use of high-damping materials
in new construction and damping treatments of existing equipment can reduce structural
resonance, in turn reducing transmission. Isolation of the man from the vehicle by means of
resilient seat cushions and the like is another method of reducing transmission. The usefulness
of this techniciue is necessarUy hmited when dealing with ejection seats. The "dynamic
overshoot" of a cushion during ejection could cause an unacceptable increase in the impact
acceleration experienced by the aviator.
The adverse effects of vibration which reach the body can, in some cases, be substantiaUy
reduced. Posture can have great effect. For example, one study of vibration transmission
through the trunk to the head showed variations as great as six to one, contingent only on
changes in posture (Griffin, 1975b). Proper design of displays and flight controls can lead to a
cockpit environment that is both more tolerable and more functional during vibration stress.
With physical fitness, training, and experience, a considerable degree of adaptation may take
place in the aviator. In addition, motion sickness induced by vibration often responds to the
standard pharmacologic remedies. To date, no other drugs are known to have an effect on
human tolerance to vibration.
2-18
Acceleration and Vibiation
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2-19
U.S. Naval Flight Surgeon's Manual
von Gierke, H.E,, & Brinkley, J.W. Impact accelerations. In M. Calvin & O.G, Gazenko (Eds.), Foundations of
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2-20
AcceleraliGn and Vibration
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19-21.
2-21
U.S. Naval Flight Surgeon's Manual
Williams, N. Biological effects of segmental vibration. /oitmai of Occupational Medicine, 1975, J7(l), 37-39.
Yugajiov, Ye., & Kopanev, V.I. Physiology of the sensory sphere under spaceflight conditions. In M. Calvin &
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2-22
u
o
o
n
■n <i 'r-ui- ^-i 'r' -
CHAPTER 3
VESTIBULAR FUNCTION
Introduction
Struc Jure and Function of the Vestibular System ■ v > ^ •
Spatid'E&eiipatfrtaon . • '
ViWal-Y#st»bwIw lateriff^^ i m h^Ki
Vestibular Contributions to Disorientation '
Disorientation Not Attributable to Strong Vestibular Stimuli - Primacy of Vision
Prevention of Disorientation
Evaluation and Management of Disorientation Problems , . ,^, ,1,^3^
Rfifere^cei , .. . . .1 .. ■ .
Introduction .
VestiWsa paMeWft mm^^m eiic«)untered by flight personnel in aviation and aerospace
missions are very similar to s^ii^ptoms reported by patients with vestibular disorders of sudden
onset. Disorientation (vertigo, dizziness, tumbling sensation), nausea and vomiting, episodes of
blurred and unstable vision, and impaired motor control (disequihbrium) are effects which can
occur singly and in various combinations as a result of either exceptional environmental stimuli
or episodic ve§l3b||lflff!!#fQr#Wi Qfj^feothv li^.tl»eKftWfiy>» enT^onnwn^^^ ^pfltoias jmj he
normjiJl se^ptiianS! mirtte^disng or inadequate^ js^©yy stimuU, but they may be coupled with
requirements for controlling a high performance aircraft in three-dimensional space. In
pathological states, the symptoms result from disordered transduction or central processing of
head accelerations, and this is likely to be coupled with requirements for control of head and
body motion. In either case, the origin of the al;»errant reaction^ Ues, in inadequate or misleadU^
information about the 04,43^0^011 and/or -arieHtfttioa of Jjq% r^lp© fe>
H|t«ni^lf -thfejeomtitVltfiS ftljit^^^ to survival. It is natural, then, that unexpected occurrences
of such reactions can be very disturbing. The parallel between pathological states and
exceptional environmental conditions can be taken further. When unnatural motion conditions
are frequently experienced, a state of adaptation is frequently achieved m which^the disturbance
and disequilibrium initially elicited, gradually abate; perceptiorial' aberra^oris ^feappear, and
coii^^' of motion approaches a desirable state of automaticity. A similar process occurs in
disease states. Disordered sensory inputs are compensated by central adaptive processes. As a
matter of fact, the adaptive process sometimes keeps pace with a very gradual loss of function,
such that no symptoms are experienced. Attention to this parallel is of probable practical
3-1
U.S. Naval Flight Surgeon's Manual
importance to both the civilian practitioner and the specialist in aviation medicine. An
understanding of the perceptual aberrations and reflexive actions generated by unusual motion
stimuh and the process of adaptation to those stimuli may increase our understanding of the
symptomatology generated by various disease states, and of course, the converse is also true.
Structure and Function of the Vestibular System
The vestibular system, almost like sensors in an inertial guidance system, detects static tilt of
the head relative to the Earth, change -in-orientation of the head relative to the Earth, and linear
and angular accelerations of the head relative to the Earth. These sensory messages are set off
early in life by passive, involuntary movement, and they probably play an important role in
development (Guedry & Correia, in press; Ornitz, 1970). Not lorig thereafter, however,
vestibular messages are frequently eUcited by active, voluntary movement, and then they play a
role in development of skill in the control of whole-body movement. In ambulatory man, the
head is the uppermost motion platform of the body, and to be functional, vestibular messages
must be integrated with proprioceptive and visual inputs. Vestibular messages coordinate with
these other sensory systems in setting off reactions that reflexly adjust the head, eyes, and body
for automatic control of motion.
In this chapter, it is assumed that the reader is familiar with the basic anatomy and structure
of the vestibular system. However, as a reminder, some basic information about this system will
be presented along with a nomenclature convenient for describing stimuh to the vestibular
structure. Figure 3-1 illustrates anatomical features of the semicircular canals and of the utricle
and saccule. The major planes of the semicircular canal ducts relative to the cardinal head axes
are shown in the insets. A gelatinous cupula protrudes into the ampulla of each semicircular
duct and serves as a sensory detector of angular accelerations in its plane. Gelatinous pads, one
in the utricle and one in the saccule, have calcite crystals imbedded in their surfaces and are
sensory detectors of linear accelerations of the head. Note the acute angle of the small ducts
connecting utricle and saccule. With saccular destruction, the small duct to the utricle may
close, possibly preserving the functional integrity of the utricle and semicircular canals. This
possibility is speculative, but it may account for early experimental results indicating lesser
equilibration disturbance after saccular as compared with utricular ablation. Utricular ablation
would destroy the integrity of both the semicircular canals and utricle.
Stimuli to the Vestibular System
The vestibular apparatus consists of two distinctive kinds of sense organs: (1) The cupulae in
the ampullae of the semicircular canals respond to angular accelerations that occur as head turns
start and stop; (2) the otoUthic sense organs in the utricle and saccule respond to linear
accelerations of the head or to tilting of the head relative to gravity.
3-2
Vestibular Functibn
^ 3-3
U.S. Naval Plight Surgeon's Manual
Each semicircular canal is stimulated by angular acceleration, a in its plane. If there is an
angle /3, between the plane of the canal and the plane of the angular acceleration of the head,
then the effective stimulus to the canal, a^, is given by
ttg = a cos ^(
This means that if the horizontal canals lie in the plane of a, stimulation of the two vertical
canals would be zero since cos 90° = 0.
Angular acceleration is independent of the distance from the center of rotation, and the
semicircular canals are not responsive to linear accelerations, probably due to the close
similarity in specific gravity of the cupula and the endolymph. Recently it has been suggested
that substantial contact between the cupula and the interior membranous ampullary wall, all
around the periphery of the cupula, would limit deflection of the cupula to its central portion,
hke the movement of a drum. If correct, this could further reduce responsiveness of this system
to linear acceleration. Therefore, a person seated with head erect at the center of rotation of a
vehicle undergoing angular acceleration would receive the same stimulus to the semicircular
canals as another person seated with head erect five meters or farther from the center of
rotation. The latter would, of course, be exposed to much greater centripetal and tangential
linear acceleration, and hence a different otolith stimulus than the former, but the stimulus to
the semicircular canals would be theoretically identical.
Analysis of the inertial forces and torques which displace the utricular and ampullar sense
organs involves a branch of physics referred to as kinetics, but these forces and torques are
proportional to linear and angular accelerations of the head. Therefore, the commonly used
kinematic descriptions of linear and angular accelerations of the head are sufficient for
specifying vestibular stimuli.
Linear acceleration is the rate of change of linear velocity, and it can be expressed in
cm/sec.2, m/sec.^, ft./sec.^, or g-units. Acceleration is expressed in g-units when it is given in
multiples of 32.2ft./sec.2 (i.e., in multiples of the acceleration that Earth's gravity imparts to a
freely falling body). When linear acceleration is represented as a vector, the arrowhead points in
the direction of acceleration and its length represents its magnitude, but in order to be
physiologically meaningful, it must be "man-referenced." A convenient nomenclature for this
purpose is presented in Figure 3-2.
The classical view of semich-cular canal function has been challenged by results suggesting that responses
initiated by the semicircular canals are modulated by changing linear accelerations (Benson, 1974a). This issue
is not yet resolved and this chapter assumes that the classical view will prevail.
3-4
^^^^ Vestibular Function
Linear Acceleration Angular Acceleration
Ufiwerd Acceleration Yiw Left ,
^ ) Figure 3-2. Polarity conventions, planes, and cardinal axes of the head. Linear and angular accelerations are
vectors that most be specified in i^aiffon to anatomical coordinates of the head in order to be properly
described as vestibular stimuli. These head axes, as defined by Hixson, Niven, and Correia (1966), provide a
clear anatomical reference to which stimulus parameters can be related. Relations between this and the
ncmiendature used in Oiapter 2 are clarified in lig^ •
Angular acceleration (a) is the rate of change of angular velocit}^ (co), and it can be
expressed in any angular unit like deg./sec.2 or rad./sec.2 However, the radian (rad.) must be ^
used in formulae for calculating instantaneous linear measures from angular measuBes wlien fcfe
radius is known. Angular acceleration cam also be represented as a vector, as illustrated in
Figure 3-2. The angular acceleration vector must be drawn in alignment with {or parallel to) the
axis of rotation, and its arrowhead end is determined by following the right-hand rule: When
angular velocity is increasing, point the curled fingers of the right hand in the direction of
rotation, and when angular velocity is decreasing, point the curled fingers oppds!td'ti&''iili^lWc>A"
of rotation; in e%ch ea^, the thijmb d^termiitteS! fee lifeie&iri of the arro'H^1?^dV iiiko^ the a
vector is perpendieular to the plane of rotation, a simple way to envision its effectiveness in
stimulating, a semicircular canal is to imagine that the canal has an axis. If the a vector and canal
axis are aligned, then a would be maximally effective in stimulating the canal. The angle
between the canal axis and the angular acceleration vector is the same as the angle ^ mentioned
in a preceding paragraph. Thus, (Figure 3-2) would stimulate the lateral (or horizontal) canals
and not the vertical canals.
3-5
U.S. Naval Flight Surgeon's Manual
Sensory Transduction of Head Motion into Coded Neural Messages
There is spontaneous activity in the vestibular nerve. If the head starts to turn left about the
z-axis the rings of endolymph in the two lateral (horizontal) canals tend to lag behind due
to inertia, thereby deflecting the cupulae, as illustrated in Figure 3-3. In the lateral canals,
deflection of the cupula toward the utricle (utriculopetal deflection) increases the rate of firing
of the left ampuUary nerve, while deflection away from the utricle (utriculofugal deflection) in
the right lateral canal decreases the firing rate. Therefore, for this particular head movement, the
two lateral canals provide a synergistic push-pull input (increased discharge frOm the left and
decreased from the right) to the central nervous system (CNS), while neural input from the two
vertical canals, being at right angles to the plane of angular acceleration, remains at spontaneous
level. In the vertical canals (the anterior and posterior canals), utriculofugal cupula deflection
increases firing rate, while utriculopetal deflection decreases it. Thus, for each different plane of
angular acceleration of the head, the canals provide a unique pattern of sensory inputs which
can be "interpreted" by the CNS so that compensatory reactions in the appropriate plane are
produced. Note that the ability of each canal to increase or decrease the rate of discharge of its
ampullary nerve has important functional significance. It means that a single canal is capable of
signahng rotation in either direction in its plane, and furthermore, that a single intact inner ear,
due to the orthogonal arrangement of the three semicircular canals in each ear, is capable of
signaling direction of rotation in any plane of head rotation. Figure 3-3 is also convenient for
visualizing expected initial reactions to peripheral vestibular disorders.
The otolithic sensory organs in the utricle and saccule respond to linear acceleration and to
tilts of the head relative to gravity (Figure 3-4). Calcite crystals at the surface of the gelatinous
placqueg that comprise the utricular and saccular sense organs have a specific gravity of 2.71 ,
much greater than that of the surrounding medium, and this property is responsible for these
organs acting as density-difference, linear accelerometers. The surface of the utricular otolith
membrane is sUghtly curved, but its plane is approximately parallel to that of the lateral
semicircular canals. Linear acceleration, acting par&Ilt;l to the plane of the otolith membrane
(frequently referred to as the "shear" direction), is considered the effective stimulus to this
sensory system (Fernandez, Goldberg, & Abend, 1972). Therefore, a rightward Unear
acceleration of 245 cm/sec.^ (equivalent to .25 G) would produce a leftward shifting or sliding
of the otolith membrane (relative to underlying hair cells [Figure 3-4B]) that would be equal to
that produced by tilting the head 15 degrees to the left (Figure 3-4C) because the "shearing"
component of the stimulus would be equal in both situations. Actually, a suitoined rightward
linear acceleration of 245 cm/sec.^ is perceived as a leftward tilt of approximately 15 degrees.
As in the ampullary nerves, there is spontaneous firing of the utricular and saccular nerves.
3-6
VestiWar Puflctioii
Hair Ceil
Hair Cell
Comparator
Conciition
Discharge !
-Parttem —
Head
Stationary
Head
Left
Left Ear
Hyperact,
' 1
1
1
1
Left Ear
Hypoact.
i
Figure 3-3. Direction of endoiymph displacement (arrows in the lateral semicircular canals) dnring angular
acceleration of the head to ihe left (counterclockwise as viewed from above). Dashed lines indicate cupula
diaplacement which deflects hairs projecting into cupula. The inset hair cell iUuatrates stereocilia relative to the
kinociliuni (dark hair). Deflection of the hair bundle toward the Idnocilium increases neural discharge, while
deflection away from the kinocilium decreases neural discharge relative to spontaneous level. Irritative and
ablative insults which result in similar GNS comparator states tend to produce similar sensations and reflex
actions (Gorreia & Guedry, in press). ■
/
a.?
U.S. Naval Flight Surgeon's Manual
1G
Force
of
Gravity
Inertial Shearing
Fo rce
.25G,
1.03G
Force
Gravity
Resultant
Otolith
, Mem bran ev
+++ +++
+ + + + + +,
'Hair Cells
/ Spontaneous \
■^Neural Activity^'
+ + +
+ + + + + +
+ + +•
Change in Activity
of Utricular Nerve
+ +
+
+ + +
+ +
+
+ + +
+ + +
+ + +
+ + +
+ + +
Stationary
Upright
Position
Rightward
Linear
Acceleration
(■Ay)
\
Force of Gravity
Static
Left
Tilt
(15°)
Figure 3-4. Spontaneous neural discharge from utricular nerve
and its modulation under various conditions.
3-8
Vestibular Function
The hair cells at the base of the utricle are shown diagrammaticaUy in Figure 3-4. Hairs
projecting upward from each cell liave a morphological polarization determined by the position
of one lone distinctive kinocihum relative to shorter rows of sterocilia (Lindeman, 1969). It has
been fotuad that idclieotien liair bundles tQWapi lih© Idn^^ftertrteigfiJias^! ^^
discharge rate, whereas ofp©site deflection decreases the discharge rate relalii?»''tO'''Hli^
spoiltaaaeottl lev^. AE eeBs "-peijlt" toward a hook-shaped striola that curves through the
macular utricuU, and a similar arrangement exists in the saccule. It is also the morphological
polarization of hair cells in the cristae of the semicircular canals that determines which direction
of cupula deflection increases the neural firing rate. Therefore, direction of tilt of the head is
signaled by different topographical patterns of discharge in the utriculEur nerve. For example, if
the head wettt i£t^d forward, the cells d»pfeMi in it^oiitia l»$\iittaiP(«^^:Vi##lhe
sp^:rtMteouS firing mte would be maintained, gad ©ther ceUs in oifefr locations within the
macula would alter neural activity. Amount of tilt in a given direction would be signaled by the
amount of change of a specific unique pattern relative to the spontaneous firing level.
The otoUlhic rgeeftt« agpetir to have Jj^ (Fernandez &
Goldberg, 1976; Golidbetg fi^ l^ptpandez, 1975), i.e., in addition to signsaling static position of
the head relative to gravity, some nerve fibers from the utricle and saccule respond to change in
position. These latter units respond when the otolith membrane is moving relative to the
underlying hair cells, thus they respond to change in linear acceleration. This ability of the
otolithic receptors to supply both position and change-in-position information wiU be discussed
hfki0 in tmas of their pot©ntijd. eont||huti^ tq;spati4«rien^ NKirophysiologicpl studies
also indicate that with sustained tiltj there is some evidence of adaptatioi) ij^ ij^^
"pOSition-se^sitiYe^" units. _ ^ .
I.. . ...
Acceleration Principles and Nomenclature
Einstein's Equivalence Principle and Spatial Orientation. In dealing with hnear acceleration,
it IS: impoiiant to recognize the equivalence of the effects of linear acceleralMfi and gravity.
Einstein's equivalence principle states that a gravitaMonal field of force at any point in spfei ii
M every way equivialent to an artificial field of force resulting from linear acceleration. In
Figure 3-4B, the reaction to linear acceleration was resolved with the effect of gravity to yield a
resultant vector of 1.03 G. Assuming that this condition is sustained, a person experiencing it
might be expected to feel tilted about 15 degrees because he is tilted 15 degrees relative to the
existing force field.
Also, according to Einstein, space is isotropic, i.e., vertical is not a special dimension, it only
seems that way because of man's limited view of the universe. However, we are dealing with
man, whose perceptions develop from a very limited view early in hfe and expand somewhat
with experience, yet, many effects of ontogenetic and phylogenetic development remite.
U.S. Naval Flight Surgeon's Manual
Moreover, in the practical business of landing an aircraft or even walking on Earth, the vertical is
a special dimension which must be accurately estimated one way or another. From the point of
view of understanding spatial orientation, it is important to recognize the equivalence of linear
acceleration and gravity while remembering that man usually operates as though the vertical and
horizontal are special dimensions. Thus, when a linear acceleration and gravity are vectorially
resolved to give a new direction to the acceleration field, this new direction may be accepted by
the man as vertical, depending upon his perceptual and intellectual assessment of how his
position was attained. Pilots learn that the resultant of gravity and an accelerative force in flight
can seem to be vertical when it is "tilted" relative to Earth.
An Example of the Use of Acceleration Nomenclature. Consider a pilot (Figure 3-5) in an
aircraft that increases speed at constant rate for ten seconds in going from 440 mpb to 500 mph
during level flight, i.e., a speed change of 60 mph. The aircraft imparts a linear acceleration to
the pilot along his x-axis, and it has a magnitude of 8.8 ft./sec.^ By the nomenclature, the sign
of this acceleration relative to the man is defined as positive, and the magnitude is indicated by
the length of the vector, which would be 8.8/32.2 or 0.27 of the length of the arrow designating
the magnitude of gravity. Thus the linear accelerations, expressed in g-units, along the head axes
are = + .27 g. Ay = 0, and A^. = +1 g.
Now consider the flight engineer in Figure 3-5 seated facing an instrument display on one
side of the aircraft. While the aircraft is accelerating, his linear acceleration can be described by
Ajf = 0, Ay = —.27 g, and A^ = + 1 g. The resultant has moved from his z-axis toward his y-axis;
it has rotated in the y-z plane about the x-axis as shown in Figure 3-5. The resultant vector, Ay^,
makes an angle, = 15.3 deg., with the engineer's z-axis. (The positive sign of the angular
displacement, tp^ , can also be established by the right-hand rule of rotation. When the thumb of
the right hand is pointed along the + x head axis, the curled fingers point in the direction of
rotation.) The two men receive the same acceleration, but the physiological effects are different
because the men are oriented differently in the aircraft. If the direction of the resultant
acceleration in Figure 3-5 (A^g for the pilot and Ay^ for the flight engineer) is accepted as
upright, the pilot will perceive a backward tilt and the flight engineer will perceive a leftward
tUt. However, both would be likely to perceive a nose-up attitude of the aircraft, assuming that
each is aware of his orientation relative to the aircraft.
Representation of the Direction of Gravity. In Figure 3-4, the vector (G) representing
gravity is a downward-directed arrow, whereas in Figure 3-5 it is an upward-directed arrow
(g). This inconsistency was purposely introduced to illustrate that there is some variation
in aerospace medicine in regard to the directional representation of force vectors. There
a choice as to which of the following shall be represented — (l)the action of a force on
3-10
Vestibjilar Function
.8 . i<il'':t
Figure 3-5. Different perceptions of tilt in a pilot and flight engineer in an aircraft accelerating during level
flight. The resultant of the linear acceleration and gravity rotates toward the x-axis in the pilot and toward the
y-axis in the flight engineer.
341
U.S. Naval Flight Surgeon's Manual
the body, or (2) the reaction of the body to the force. When an aircraft in level flight
increases forward speed, vectorial representation of the acceleration and of the force applied
to the pilot by the back of the seat would be forward, as illustrated in Figure 3-6A. The
body reacts to this force by an equal and opposite backward-directed (inertial) force
(Figure 3-6B), and since the body is not rigid and is not of uniform density, some organs
within the body will be displaced slightly backward relative to the skeletal system. Likewise,
the seat is applying an upward-directed force, equal and opposite to the weight of the man
on it. However, the effect of gravitational attraction is to displace organs downward relative
to the skeletal system, just as though the man were being accelerated upward. If actions
of the seat on the man are represented, i.e., if the forward acceleration is represented by
a vector pointing forward, then gravity must be represented by an upward-directed vector
as in Figure 3-6A. If reactions are represented, i.e., direction of displacement of body
organs relative to skeletal system, then the x-axis vector must point backward and the
gravity vector downward as in Figure 3-6B. Note that the length and line-of-action of
resultant vectors (heavy black arrows) are the same in Figures 3-6A and B, whereas the
resultant line-of-action represented in Figure 3-6C is incorrect because a mixture of action
and reaction vectors has been used.
Coding of Vestibular Messages
In the aerospace environment, unusual linear and angular accelerations occur frequently.
The occurrence of a single, exceptional linear or angular acceleration component can induce
disorientation or vertigo, but more typically, one must consider combinations of stimuU to
appreciate troublesome situations. To comprehend the functional significance of unusual stimuli
combinations, it is helpful first to appreciate the coding of normal vestibular messages that
occur in natural movement (i.e., movement not involving vehicular transport). In natural
movement, whenever the head is tilted away from upright posture, the semicircular canals and
otoliths always provide concomitant, synergistic messages. For example, during backward head
tilting from upright posture, change in neural activity from the four vertical canals and absence
of change from the two horizontal canals is a coded message to the CNS signifying angular
velocity of the head about its y-axis, -<Jy. Concomitantly, changes in neural activity would be
generated by the otolithic receptors. During the head tilt, the utricular otoliths would slide
backward, triggering change-in-position receptors as well as position receptors in a pattern
signifying a position change about the y-axis, and the final coded utricular position information
would be predictable from the preceding change-in-position information. Likewise, it has been
shown that integration of the angular velocity information from the semicircular canals can be
subjectively performed to obtain an angular displacement estimate equal to the position change
which has occurred (Guedry, 1974, pp. 50-56), and hence, equal to that signaled by the
otohths. When the head is turned about an axis that is aligned with gravity (for example, the
3-12
(A)
(B)
(CJ
Forward Acceleration
CO
Reactions to
Forward Acceleration
+G,
A^ (Action V«c*j)r>
+G2(Reaction Vector)
I
Ef.
§
Action Vectori
Mixed Action and
Reaction Vectors
(Incorrectl
Figures^. The direclSbnai i^i^ttlatiim of aclfen and reaction vectors. The line of action of the resultant vector .s
incorrect in (C). In aviation medicbe, reaction vectors are frequently used, and gravity is often symbolized by G and a
downward-directed vector. For man-referenced reaction vectors, +G, is usually defined as tfark^d.to-8^ diJ«5ti<wi (»ee
Chapter 2), whereas fof action vectors as defined by Figure 34, is defined as ihe seat-to-Head direction.
U.S. Naval Flight Surgeon's Manual
head turns about the z-axis in upright posture or about the y-axis while lying on one side), the
semicircular canals are stimulated, but there is no change in orientation of the otolith system
relative to gravity, and hence, no change-in-position information from the otolithic system.
Under this circumstance, i.e., when the axis of rotation signaled hy the semicircular canals is
aligned with the gravity vector as located by the otoUth system, these two classes of vestibular
receptors do not reinforce one another, but it should be noted that there is no conflict in their
information content.
Consider now the situation depicted in Figure 3-5. During forward acceleration of the
aircraft, the resultant Unear acceleration, 2, rotates from alignment with the pilot's z-axis
forward toward his x-axis through an angle designated as +4>^. As was pointed out earlier, this is
the same change relative to the existing force field that would occur if head and body were
simply tilted backward relative to gravity 15 degrees. However, during the "tilting" process, the
vestibular message would be quite different in these two situations. In the latter situation (real
tUt), the synergistic messages from the semicircular canals and the otolithic receptors as
described above would be present. Degree of backward tilt would be quickly and accurately
perceived. During the dynamic phase of the stimulus in the former situation (forward
acceleration), change-in-position and position information from the otolithic receptors would be
unaccompanied by synergistic information from the semicircular canals. "Tilt" relative to the
resultant ,Ax 2, would be greatiy underestimated or not perceived at all (cf. Guedry, 1974,
pp. 106-108); rather, the individual would perceive forward linear velocity, i.e., he would
perceive what is actually happening. However, if the forward linear acceleration is sustained for
a while, then, in this "steady state" condition, the otolithic position input would signal tilt, and,
as in static tilt relative to gravity, otoUthic or semicircular canal change-in-position information
would be absent. In this case the individual would experience backward tilt as though he were
tilted relative to gravity, but only after a delay or lag. Each of the conditions just described,
except sustained horizontal linear acceleration, occurs in natural movement, and each produces
a pattern of vestibular input that is familiar and perceived quickly and accurately if the observer
chooses to attend to it. In subsequent sections of this chapter, conditions of motion will be
described that produce conflictual vestibular inputs, and these are usually confusing, disturbing,
disorienting, and nauseogenic.
In partial summary, the semicircular canals localize the angular acceleration vector relative
to the head during head movement and contribute the sensory input for (1) appropriate reflex
action relative to an anatomical axis and (2) for perception of angular velocity about that axis.
Perception of how this axis is oriented relative to the Earth depends upon sensory inputs from
the otolith and somatosensory systems, and thus, appropriate reflex actions relative to the Earth
depend upon these other systems working synergistically with the semicircular canals. The
3-14
Vestibular Function
otoliths provide both static and dynamic orientation information (relative to gravity) and
contribute to the perception of tilt and also to the perception of linear velocity. The perception
of linear velocity derives from a combination of (1) change-in-position information from the
otoliths and (2) the absence of angular velocity information from the canals. The otoliths
provide change-in-position informatioii -vfhm Hie cilia are in motion, and the stimulus required
is change in linear acceleration.
Spatial Disorientation
In an aviator, spatial disorientation usually refers to the inaccurate perception of the
attitude or motion of his aircraft relative to the coordinate system constituted by the Earth's
surface and ^avitational vertical, and it can endanger flight safety. Spatial disorientation has
been estimated to account for between four and ten percent of major military aircraft accidents
and even higher percentages of fatal accidents (Gillingham & Krutz, 1974, p. 66; Hixson &
Spezia, 1977). In private civilian aviation in the U.S. from 1964 to 1972, disorientation and
closely related categories accounted for 37|lPereent of afl fatal accidents (Benson, 1974b).
Disorientation is a normal reaction in many conditions of flight, and it is probably
experienced by all pilots at one time or another. Common experiences with disorientation are
hsted in Table 31. It illustrates that there are similarities in disorientation encountered in
different types of aircraft and also across a span of 14 years (Clark, 1971). Table 3-2 fists some
common disorientation inctdente in U,S. Navy helicoptec operations (Tormes & Guedry, 1975).
The iraplicationfi of disorientation incidents range from fatal accidents to inconsequential
events that may be instructive to the pilot. Between these extremes are nonfatal accidents,
aborted missions, mission degradation, and mission completion but with persisting unfavorable
effects on the pilot. A number of factors combine to determme the, consequences of a
disorientation incident. Clesttly oiie fKctot is yrhm swd vrhm. the incident occure. Sufficient
altitude wltTil no oftiir ^lane'or objeet nearby &m provide, abundant recovery time and reduce
rWk^and conversely, proximity to the Earth's surface or other aircraft increases risk. This factor
and its relations to items in Tables 3-1 and 3-2 are obvious and will not be elaborated here, but
it is a factor that predominates and influences all others. A factor, not quite so obvious, is the
pilot's state of awareness of disorientation when it occurs. A pilot may be considerably
dmoriented, but he attay be tintware of it. His cojatrol actions, based upon perceptual
KiisinfOrmatlon, wiU tpKice him at rislt. When the action is taken, the response of the aircraft
may prompi m iristru^ent ^eek which ordinarily vnR lead to proper corrective action. An
important exception may occur when the conflict between an immediate false perception of
aircraft orientation and instrument information provokes an excessive emotional reaction; then
the pilot remains at risk.
3-15
Percentage of Pilots Reporting Disorientation
in Current Aircraft Compared with the Percentage of Pilots Reporting in 1956
CO
uison email on inciaent
Pereentages for Vatfous Aiicraft
Typesahd Situations
Data
from
1956
Transport
N-65
Training
N=105
High
AltllUGie
N=39
Single
Plaee Jets
N=13
Helicopter
N=99
N=137
Sensation thipt oiie wing was down (wings actually level)
71
67
41
85
52
67
CD "P i_
reixsiraignTana tevei, Dtft in Fe&fity^ lin a turn
When leveling off after bankj tant^rii^ to overbank in opposite
direction
40
42
40
40
44
46
46
92
34
44
66
67
Airci
Attiti
Errc
During Instrumem flight, leaned fb right in cockpit to keep self
vertical
29
36
31
46
29
45
During straight and level, felt in a bank
After steep, climbing turn, felt turn in opposite direction, but
instmpents ii^du^^ied^aiEitttarid leiwl .
60
•a*
56
59
23
85
46
42
31
75
Ss-
a
o c
-Gomnfng out Of tfiick^^bast, «em«d hortzon was severely tilted
thtjuc^i was atiuaify straight ar»d leVel
25
19
38
46
9
20
Visual
teferen
'robler
Flare on dark night seemed to move on w-ratte:eiiww,#ut in
reality, it was floating straight down
18
15
3
31
33
23
Urn
Confus«d orv dark nif^ht about stars and surface lights; resulted
in uncertainty eibo^tpositiojj <]«|; hodzon.
48
30
49
92
29
__
icker
Sunlight^h^gh prcipi^ll^^us^ flU:km; orBw mem ber became
confu»d and very uhdSitifbrtabfe
14
10
3
0
26
--
u.
Flying through fog, became confused by rotating beacon on
aircraft causing flickering light in cockpit
42
23
28
46
22
hie
ItlOfl
Although irf complete control of plane, lost sense of direction;
thought flying east, when actually flying north
23
51
28
54
53
47
= 1
ll
On routine patrol flight, had feeling of not knowing location and
mbrn^Hatlly titrned'arauntf in dilrsietion
34
«
26
38
46
m
D
Had fun view of bay with lights around it; seemed like totally
strange place, though usually quite familiar
23'
25
15
31
34
27
in
Z
EL
O
s
I
Table 3-1 (Continued)
Percentage of Pilots Reporting Disorientation
in Current Aircraft Compared with the Percentage of Pilots Reporting in 1956
CO
J
I— 1
-4
Disorientation Incident
l^centages for Various Aircraft
Types and Situations
Data
from
Transport
N=65
Training
N=105
Higii
Altitude
N-39
Single
Place Jets
N=13
Helicopter
N=99
N«T37
if
Fol!<»Nlh0 loss of altitude while malnttining constant heading,
ears cleared, and felt to be in a turn
9
12
10
8
3
Following climb on constant heading, felt bank wwhen straight
and level (possible presajre vertigo)
26
29
18
15
21
III
Very intmt on taiget and didn't checl< altimeter. Suddenly
realized vws too low, abruptly pulled out with only few
feet to «pare
14
11
3
-I
23
15
12
Resti
lostru
Sc
Became confiised in attempting to mix contact and instrument
cues for orietttatipn
37
a
44
38
31
m
S
A °
Climbing to high altMode, had fe(i4iria <5* isolation and of
being separated^ from eartiK
23
22
15
38
24
33
Cross- 1
wind
OnilrB^nd landii^, tttftfcw^rffttno ibad^ across
ruiiHAy , but failed tomake «iv coraiK^^
15
22
8
0
8
12
(AdBptiMi from Claric, 1971K
U.S. Na*d Mij^t Surgfe6il'8 Manual
Table 8-2
Survey of Helicopter Pilot
Disorientation Experiences
Described Circumstance
I'ercentage
of 104 Pilots
Reporting
Disorientation
Sensation of not being straight and tevel after hank and turn ("thf [earn")
Low altitude hover over water, niglit
Reflection of anti-collision light on clouds and fog outside the cocicprt
Transitioning from IFR to VFR and vice versa
Misinterpretation of relative position or mbvemeift of ship during night apprbach
Head movement while in bank or turn
Landing on carrier or other aviation ship, night
Night transition from hover over flight decl< to forward flight
Mispereeptlon of true horizon due to sloping cloud bank
Inability to read instruments due to vibration
Take-off from carrier or other aviation ship
Reflection of lights on windshield
Awareness of flicker of rotors
IVIIsperception of true horizon due to ground lights
Fatigue
Distraction by aircraft malfunction
Formation flying, night
Misled by faulty instrument
Vibration
Misjudgment of altitude following take-off from carrier or other aviation ship
Going IFR in dust, snow, water, in low hover
Loss of night vision -
Take-off or landing in strong crosswrnds
Symptoms of cold or flu i
Low altitude hover over water, day
Formation flying, day -
Low altitude hover over land
In-air refueling from moving ship ■ .
Self-treatment with over-the-counter drugs '
Landing on carrier or other aviation ship, day
or
81
70
62
58
56
51
49
47
45
39
36
35
33
32
29
25
25
24
21
19
15
13
IT
10
8,6
6.7
2.8
1.9
0.96
(Adapted from Tormes & Guedry, 1975).
3-18
Vestibular Function
On the other hand, there are many maneuvers which induce disorientation, but the pilot is
so aware of its occurrence that he may not be at aU disturbed by it. For example, a plane flying
in a level, coordinated, gentle bank itnd tett- WJ^tlie perceived as though- 4|».WJ§. iii'
straight'an(i4evel.|iigJjt> for reasons mad^ (slear ia earlier se^jtions and illustrated in Figure 3-7.
The pilot who i«Bitiatts the TOJBieuver knows what to expect, and for this reason, the perceptual
experience seems "natural" and is consistent with the intellectual information derived from his
instruments. A pilot may not even refer to a false perception of the plane's attitude as
disorientation if he is keeping track of the flight situation. This was illustrated by comments
from an experienced F-4 pilot who, wMe • aerviiig as a back^'seat sabjeet in an i^^*
experiment, reported ft«t a head movement indueed an appM^nt MU 40 d^Mse |iE©f¥d«WlE
attitude of the aircraft which :at the time was in a 2 g level bank and turn. When this experience
was later referred to as an example of disorientation, the pilot-subject denied that he was
disoriented at all because he was completely aware of the true attitude and condition of the
aircraft. This illustrates an important point. The dangerous aspects of disorientation are
considerably diminished if the pilot alertly keeps track of the true conditions of the aircraft.
When disorientation inputs become second nature to him, perceptual-motor reactions are
probably modified and, in their modified form, may even enhance his control of the aircraft.
Centrifugal
Resultant
Force
Figure 3-7. The somatogravio ta oculogravic jBJjsion. In a coordinated turn,
the aviator may accept tSie reaultwfit vector as gravitational vertical.
3-19
U.S. Naval FU^t Surgeon's Manual
There is an exception, that being the case where a pUot may have persisting, strong
disorientation, such as a severe case of "the leans," and the emotional reaction to the
dfeoa^Biattotf may impair instrumeirt l^;an and normal control function. Here, the
malttitude (mSjmpmmne^v^mk ewaaeoustp^ptfoh is unfamiliar to the pilot, and, as in
the case of the unanticipated disorientation, cotttrdl^f flie iltoaft in^ be jeopardised through
the deleterious effects of hyperarousal (cf. Benson, 1965; Malcohn & Money 1972). Several
points emerge from these considerations of the etiology of dangerous disorientation
Odaailions: (1) Familiarity with conditions that produce disorientation and a "second-nature"
^^aHpation of ite ©deiapfenee can reduce.its seriom implications and may even be useful to the
aviator? laijpe tt> tracfc (iie. intfeflectud upiktiag) df flie condition of the aircraft can
convert even relatively benign flight conditions into potentiaUy haz^dous aititations. For these
reasons, b-aining concerning conditions that can be expected to produce ilisorientation wiU have
beneficial effects, and occasional refresher training is a worthwhile measure for the experienced
aviator, especially after a period away from flying.
Visual- Vestibular Interactions Relevant to Aviator Vision
The Vestibulo-Ocular Reflex
The vestibulo-ocular reflex influences vision during natural movement much more than is
generally appreciated, and it is capable of subtle and occasional profound influence on vision in
aviation. Most physicians or physiologists tiiink of nystagmus, an oculomotor pattern which
occurs in certain unnatural motion profiles and in pathologic states, in relation to vestibular
Stiffiulatloii, hwt nystagmus is probably the least typical form of the vestibulo-ocular reflex in
healthy individuals during natural movement. A mm common oculomotor response consiste of
nearly smooth, sinusoidal eye osciUations that abnost peri'ectly compensate for head osciUations
tha.t occur during walking, running, or simply shaking one's head, as in signifying "yes" or "no."
Ftir example, in the latter situation as the head turns right, the eye turns left, thereby
compensating for Wlliil movement (cf. Benson 1972). Gresty and Benson (in preparation)
describe high-frequency components (in the range 1 to 10 Hz) in angular oscillations of
the head during i^ole-body movement and also in aircraft. It is important to note tiiat the
visual system is very poor at tracking Earth-flxed targets at these frequencies if it is unaided by
the vestibulo-ocular reflex. Therefore, tiiis reflex plays an important role in stabilizing vision
relative 'to fiie^^iarth during many kinds of natural motion. The reader can demonstrate this to
himself by h^fiffing ius head stationary and oscillating tfiis page back and forth on a desk top at a
frequency jijsl sufficient to blur the print To complete the demonstration, and this is the mix
of it, oscillate your head at the same frequency while the page remains s^tionary on the desk
top, and observe that the print remains perfectiy clear. Note also that even with much faster
head oscillations it stiU remains clear. -The vestibulo-ocular reflex wtomatically stabilizes the
3-20
Vestibular Function
eyes relative to external visual surroundings during head movements to maintain wsual acuity
for Earth-fixed targets. This is the reasoE that insKtelualS mfliotlt vestibular function i^ott,
"jumbfed vi»Dn" ctartng motion, espeeiaUy vehicular motion ini^filA^ig vibratory oseiMadon.
However, foUowing loss of vestibular, function, the influence of neck proprioception on eye
movemeiit mtma^ to improve octtlar stabilization during voluntary movement.
This highly advantageous vestibular-ocular reflex can become disadvantageous (inap-
propriate), however, in aircraft, surface ships, or ^thit moving platfetms since the head moves
in inertial space, whUe visual displays, such as aircraft instrument panels, may move in unison
with the head. If there is a tight coupling between head and display during such movement, then
at certain frequencies and peak angular velocities, the vestibulo-ocular reflex wiU interfere with
vision f or the display (Guedry & Correia, in press).
Vision and the Dynamic Response of the Cupula-Endolymph System
The probabiUty of encountering problems with vision and also with disorientation in a given
flight environment depends, among other things, on the dynamic Jeaponse of the cupula-
endolymph system to various profiles and frecpiencies of angular acceleration. Understanding
this aspect of vestibular function is therefore helpful in analyzing problems arising from
pathologic conditions during natural movement or from normal responses to unusual motion.
Because the cupula-endolymph ring has the structural characteristics of an overcriticaUy damped
torsion pendulum, its behavior and that of the responses it controls are theoretically predictable
when acceleratory movements of the head are known. Much information has accumulated to
indicate when such predictions are accurate and when they are not (cf. Guedry, 1974).
Figure 3-8 iUusb-ates predicted changes in cupula displacement relative to the skuU throughout
two motion conditions. Figure 3-8A, depicting cupula deflection during a simple, natural head
turn to the left, iUustrates several important points. Notice that the cupula deflection curve
looks Uke the stimulus angular velocity curve and not Hke the angular acceleration curve. In
natural head turns, the dynamic response of- flie end organ is that ib© input sensory
message matches the instantaneous ajigular velocity of the head relative to the Earth (hke a
tachometer), even tiiough .angukr aeceleration is the effective stimulus. For this reason, the
turning sensation (subjective angular velocity) controUed by cupula deflection is accurate dunng
and after the hirn. SimUarly, the vestibulo-ocular reflex is accurate during natural turns m that
the reflexive eye velocity compensates for tiie head velocity and stabihzes vision relative to
Earth-fixed targets.
In contrast, Figure 3-8B illusf *tes vestibular effects of an unnatiiral motion involving
sustained rotation. Inertial torque deflects the cupula during the initial brief angular
acceleration, but it is absent during tiie foUowing constant angular velocity. Consequentiy, the
3-21
U.S. Naval Flight Surgeon's Manual
cupula, because of its restorative elasticity, returns toward rest position. Then, being near rest
position when deceleration oeeius, it is deflected in the opposite direction by the inertial torque
ftom the deceleration <atigakr acceleration in the opposite direction). The turmng Sensation
controlled by cupula deflection is accurate only during the initial accaleration. During constant
velocity, the sensation of turn wiU diminish and stop; then, the deceleration wffl produce a
reversed sensation of turning which can persist for 30 to 40 seconds after stopping. Obviously,
with the unnatiiral stimulus, the semicircular canals do not perform their velocity indicating
function satisfactorily, and their input can be the baris of Orientation and impaired visual
performance.
Angular
Acceleration
of the
Head
o
i
I
I
!
i '
1 / i
Cupula
Deflection
1 sec.
(A)
V
Figure 3-8. Comparison of cupula deflection during a natund it(M ttini (A)
and during a sustained turn of sweral rCToluticms r'
3-22
Vestibular Function
This unnatural stimulus produces the particular pattern of oculomotor response called
nystagmus. During the initial acceleration in Figure S-SB, tiie eyes ditft rf|Kt (relatlvi to the
skuU) as the head turns left This drift, which compenaateB appraxiwiatdy im the turn, is caUed
the slow phase of aystagmus, but as the head continues to turn, the eyes "recenter" themselves,
i.e., catch up. by a fast or saccadic eye movement called the fast phase, which has extremely
high velocity (300 to 600 deg./sec). Because the directions of the slow and fast phase of
nystagmus are opposite, there has been inconsistency in designation of tiie direction &f
nystagmus. When viewed hy a medical eJcanmiei', the fast phase (saccade) is easiest to see, and
thife fed to the convention of designating nystagmns direction by its fast phase relative to the
examinee. However, owing to recent strong chnical interest in quantification of nystagmus
(eleclronystagmography - ENG) which emphasizes measurement of slow-phase velocity,
designation of slow-phase direction has gained popularity. To avoid confusion, it is best to
specify slow or fast phase when nystagmus is described. Figure 9 iUusttAtes IMG as it typicaUy
appears when angular displacement of the eyes relative to the skuU is recorded and also when
the slow-phme velocity of each nystagmus waveform (beat) is quantified and plotted. The slow
and iast phaseslcreate the sawtooth pattern. As the head commences to turn left during the
initial acceleration, the eyes drift right (slow phase), adequately compensating for the head
velocity. With continued rotation, the eyes catch up (fast phase) and then recommence drift.
During the period of constant head velocity, slow-phase eye velocity, as it abates, would be less
and less effective in assisting the eye to see Earth-fixed targets. During deceleration, the reversed
direction of nystagmus and its persistence after stopping could only impair vimm for either
EatlM^ed or head-fixed targets.
The nystagmus iUustrated in Figure 3-9 approximates a typical response recorded in
complete darkness. The maximum slow-phase velocity iUustrated is 100 deg./sec. The nystagmus
of a person with vision restricted to the interior of a rotating vehicle would be suppressed by
any visible head-fixed display. With visual suppression, a maximum slow^hase velocity of about
l#deg./sec. (in otfver Words, the. visual/vestibular fixation index is about 0.14) would occur.
This is sufficient to degrade visibility of fine detail on instruments briefly, until the suppressed
vestibular nystagmus abates somewhat. The degradation is far less, however, than the total
blurring of vision that would occur if the 100 deg./sec. slow-phase velocity were unsuppressed.
There are a number of conditions tiiat influence visual suppression, mh oscillatory
motions, the frequency of oscillation is very important. During low-frequency, whole-body
osciUation (e.g., .01 Hz), the gain of the semicircular canal output response (peak slow-phase
velocity/peak stimulus velocity) is low even in darkness, and the visual fixation index is
favorable (.14± .05 S.D.), so that visual fixation is apt to "win out" over vestibular nystagmus
even with fairly high peak stimulus velocities. However, with high-frequency head oscillations
3-23
60 sec,
Angular
Velocity
of the Head
to iatih
Cuputa
cu
Angular
Movement
of Eyes
Relative
to the Head
-20"
Slow PhasB Velocity
I
Slow niase Velocity
Angylar Displacement of Eyes
Angular Velocity of Eyes
Figure 3.9. Electronystagmogram of cupula deflection and eye movements during and after pmboged rotation.
Measunng the dope of the angaliir displacement tracing durii^ a dow phase pv^Btfe sl«w pha^velt>ly of ^ eyes.
c
o
Veatal^wr FvnctiQii
(e.g., 1.0-5.0 Hz), the gain of the vestibular output response is high (Benson 1970, 1972), and
moreover, the fixation index becomes unfavorable. It approaches one, tantamount to little or
no visual suppression. Thus, vision for head-fixea tit|^i^«il Ae very pooT^»ttiough thkfWm
head velocity may be only 15 to 20 deg,/0ee. and Hie angle of oscillation only a few degrees
(Barnes, Benson, & Prior, 1974). ^ it .t .
'Ill;
Individual differences in visual suppressifin of vestibular nystagmus in apparently healthy
persons can be quite large. A small amount of practice improves the visual fixation index (VFl)
substantially in many but not in all persons. A fact that could be very important to an aviator is
that a small amount of alcohol, two or three social drinks, degrades the VFI and associated
visual acuity substantiaUy for about four hoHW pWiSdEy^itMlspji^iSchroeder, & Collins, 1975).
(^^,|dte of influence on the VFI is the cerebellum, particular^,^JI|^^||9p(j^rC|#b©^ggr Sl
Fttchsl 19745 Mitess& FuUer, 1975; Takew.Q4.& Cohen, 1974).
Nystagmus in the absence of unnatural (notion stiinuU is a clinically significant sign,
although positional nystagmus can occur during alcohol intoxication (Position^ Alcohol
Nystagmus I - PAN I), and it can return, though reversed in direction (PAN II), during
"hangover." Some pathologic states reduce or eliminate visual suppression of nystagmus, and
for this reason the VFI is a useful adjunct to other tests in diagnosing CNS disorders such as
multiple sclerosis (Baloh, Konrad, & Honrubia, 1975; Ledoux & Demanez, 1970). However, in
many pathologic states, especiaUy peripheral vestibular disorders, visual suppression is effeettp.
For example, nystagmus a^Ul^dfe tO^irttoed functionjito Fi|uit^i?3).,«Sir?be
visually suppressed, and it may not be detectable by #-ect observation. For this reason, eye
movements should be recorded by ENG in darkness. Alternatively, the physician may be able to
detect nystagmus if he observes movement of the corneal bijlge updqr the closed eyeM, or if the
patient wears Fresnel lenses to blur vision.
Visibility of Cockpit Instruments .
Loss of visibiUty of cockpit instruments has been indicated! as a factor in disorientation in
aviation (Melvffl Jones, 1965; Tormes & Gue«^4'^^t);r»ol»and;»«ey <a97i) i^^^
inabiUty to read flight instruments durii^ vfflJratiba aSld turbulence as one of the conditions
common to Hie: "Jet Upset/Hhentonjenon," a situation in which pilots of large jet aircraft have
gone into severe and disasterous nose-down attitudes to compensate for erroneous sensations of
extreme nose-up attitudes (cf. Martin & Melvill Jones, 1965). Factors which may influence the
visibiUty of flight instruments, separately and in combination, are &e*T^ffl)lla*OCulttr at
high frequencies' of feead oseiUation, poor visiM spttaMf^todil^ at l^rf*etaen<^ instrument
va»ration relative to Ae head, bri^itness and #aVEteD|%Tof(|i^t fete life&lnsteHOT
]
3-25
U.S. Naval fli^t Suigeon's Manual
the complexity of the instrument display. Further complications may be introduced by
tendencies toward "grayout" from changing g-loads which may be exacerbated by vestibular
Visiliiaty Outside the Cockpit
Visibility of the Earth's surface could actuaUy be unproved by the vestibnlo-oeular reflex in
some circumstances, although there is no certamty that the complex vibrato^f ttiotioks ill Jti^t
would set off optimal oculomotor stabilization for Earth-fixed or other external visual targets.
Some maneuvers, such as several consecutive complete turns, can produce vestibular aftereffects
wltffeh tefi^tb degrade vision due to nystagmus, while also disorienting the pilot. Despite good
visui'sa^kssioij '^f 'W'^ lefl^ midimym are^miftciently strong, e.g., five turns in ten
secbjidg, Vestibuliar hyatagmiii-fifeer i^pfg^siltl^ turil cari bliir vf^ioti for bo^^tfoikprtMii-
ments and Earth reference (Benson & Guedry, 1971; Melvill Jones, 1957). It has also been in-
dicated that anticompensatory reflexes (MelviU Jones, 1964) and vestibulo-ocular accommoda-
tion reflexes (Clark, Randall, & Stewart, 1975) may degrade vision in some flight conditions.
Vestibular Contributions to Disorientatioii ^ ,.
Aircraft maneuvers may involve both unnatural turns and unusual changes in the direction
and magnitude of resultant hnear force vectors. Moreover, the seated pilot does not necessarily
continually update his orientation assessment as one does automatically while walking or
ruriiitog. Thus, both the pattern of vestibtfkr stimulation and the resjfonse to it differ from
those eftBountered in nattital moT^ent.
Somatogyral and Oculo^ral Dlusiotis
Aircraft maneuvers involving several complete revolutions (turns, rolls, or spim) tend to
produce an illusion of turning in the opposite direction just after the maneuver is completed.
Contributing to this effect are semicircular canal responses as described above.
Stitoflte and ^tlbtilar response characteristics which control the magnitud«-df the per- and
posti-otatory vestibular eeecte are the velocity, of rotation adiieved, the duration of tiie
rotsition, and, with some stimuH, the particular set of canals stimulated (Benson &
Guedry, 1971). Constant velocity need not be maintained during the turn for some illusory
aftereffect to occur. Whenever angular acceleration of constant direction is applied for several
secoAdsvthe continued cupula displaeenrent m opposed by the elastic restoring force of the
BUpida^iawfefiPK^^wlimiises deceleration^^ the elastic restoring couple works with the
inertia! torque from the "stopping" stimulus to pM»dl^^0u|mIa-overshoot. Information. from
tiie semicircular canals would therefore signal "stop" before the actual maneuver ends, and
Vestibular Function
would signal "reversed turn" from the cupula overshoot for any long-duration trianguMf'or
sinusoidal waveform of angular velocity, even though no period of constant velocity i«eEti®fieA
between the starting and stopping acceleratitMi.
This sequence of perceptual events, when observed in complete darkness, has been caUed the
"somatogyral iUusion" (Benson & Burchard, 1973). EssentiaUy the same sequence, when
observed in darkness with only a smaU head-fixed visual display in view, has been caUed iJie
"oculogyral illusion" (Graybiel & Hupp, 1946). In the latter case, the pej»ived inoti€8l of the
body is referred to Ae visible display which therefore seems to be turning with the observer.
However, the display may appear to lead slightly, i.e., be displaced from "apparent dead ahead"
in the direction of the apparent motion, and it may be slightly blurred while the vestibular
signal is strong enough to generate nystagmus in spite of visual suppression. The threshold for
Mertion of angular acceleration seems to be lower for the oculogyral illusion than for the
somatogyral illusion (Clark & Stewart, 1969). from the point of view of aviation, it is
important to note that these illu&ofy effects occur eve^i in a well-iUuminated cockpit if external
visual reference is absent or ill-defined.
There is a curious difference in the aftereffects of active and passive whole-body rotation.
The reader can demonstrate this to himself by standing and, with arms folded, executing eight,
smooth, continuous ambulatory turns in about 20 seconds with eyes closed. Upon stopping
(eyes stdl closed), if the body is allowed to rmmn isaxLj relaxe4,,%e>ead« toESO^P^iQ^ ten^
to twj^t in fte same direction as the previoif^turn. The motor, effects are in Uie m^^A
compen^atorv direction from the deceleratory stimulus to the semicircular canals; they are
compensati^ fW a body motion which is not taking place. Under this circumstance the
aftersensation in most individuals is not one of turning in opposite direction, as would be
predicted from the semicircular canal response, but rather of taming in the same direction as
the preceding turning motion. The 8pinovestib^te. feedback apparentiy dommate^,, the
perceptual expejaenee.
This demonstration has two potentiaUy important impUcations in aviation. First, it
illustrates that unusual vestibular stimuli can induce reflexive motions of the head, torso, and
hmbs that may not be appreciated by the pilot, yet they may influence performance. Secondly,
liie difference in aft^rsensttioli between ^ctive and passive turning may have imphcations tor
the pereeptiial experiences of pilots who actively generate unusual vestibular stimuli m flight
maneuvers and, of course, continue to control the aircraft after maneuvers are completed.
Experienced pilots develop what is referred to as "fusion," in which the aircraft is said to
become a mere extension of their voluntary control of motion (Reinhardt, Tucker, &
Haynes 1968). Thus, tiie sensations of cxperieiicea pHots are probably shaped by iheir active
3-27
I U.S. Naval Flight Surgeon's Manual
mn^^l ftinctions^and may be a little different than would be deduced from passive stimulation
M,mmmT^ , account for several indications that experienced pUots are
much more disturbed % fixed-base flight simulators 0Lmtm,^ mmd, 1975) with moving
visual scenes than is the novice. The likeUhood that the pilot's active control of his aircraft
reflexively shapes his perceptuid experience also lias implications for the importance of
maintaining flying practice.
SMtlttl^Hi^e and Oculogravic Illusions
fhfe' somatogravic and oculogravic iUusions are sometimes referred to as the otolithic
counterparts of the somi*6^d a«d 6ciiH>gyml illusions. They are apt to occur when the head
and body are in a force field which is not in alignment with gravity, a condition that occurs
frequently dunng flight and which is usuaUy studied in the laboratory by means of a centrifuge
Although otolith stimulation plays a role in the effects of such stimuli, certainly other
somatosensory receptors are also involved. Individuals without vestibular function experience
these "illusions," although their perceptions differ somewhat from those of individuals with
vestibular function (Graybiel & Clark, 1965).
The perception of feeling upright during a coordinated bank and turn (Figure 3-7) or its
converse of feeling tilted when the resultant force field is not aligned with gravity has been
referred to as the "somatogravic illusion" (Benson & Burchard, 1973). For situations in which
an obserVei'-We^s a Hlie'i.f light and either estimates its apparent tilt or attempts to adjust it to
apparent vertical, m jterCeptual error has been caUed the "oculogravic illusion"
(Graybiel, 1952). However, the important point for the aviator k tJiat aeceleraiibns k fligbt can
yield a resultant force vector which may be perceived as upright, even thtiugh M is ^klaatiallv
"tilted" relative to gravity.
Wlalfe the directidii ol tfie resultaiit fSorce vector provides a fairly close approximation of the
subjecbve verll^ in "steady state" conditions (i.e., conditions in which the observer
experiences prolonged static tilt relative to the resultant force vector), there are a number of
defimte departures from this rule. One such departure results from conditiorf^ (rf dynamic
^hanging over time) linear and angular accelerations, as explained in the previous discussion of
the coding of vestibular messages. During horizontal linear acceleration of an upright
forward-facing obser^, ttie rfesultant linear acceleration vector rotates in the pitch plane of the'
head and body. The otolith stimulation is as though the head" and bod^ liad rotated backward
relative to gravity, but, because the head is fixed in upright position, tiiere is no angulat"
acceleration to stimulate the vertical semicircular canals. Under these circurastanc^, the
immediate perceived change in orientation is usuaUy less than that which would be calculated
fl-om the immediate stimulus to the otoUth (Guedry, 1974, p. 105f; cf. StockweU &
3-28
Vestihidar f tsiiittefP
Guedry 1970). This kind of situation occurs inlinearly accelerating or deceleFatingaircraft, and,
though some change in attitude is experienced, if the head does not rotate oniiie neck during
the linear acceleration or deceleration, then the experienced change in attitude is probably less
than Ae dynamic rotation of the linear acceleration resultant vector and hence closer to the
actual attitude of the aircraft. Even so, there can be enough change in perceived attitude to
introduce dangerous reactions in flight (CoUar, 1946). An extreme example of Mb Mnd of
stimulus occurs during a catapult launch from m aircraft carrier (Figure 340) (cf. Cohen,
Crosbie & Blackburn, 1972). During the catapult launcKi £t p^lwmd Unear acceleration of
about 4.5 g h generated. When resolved with gravity, the resultant linear acceleration vector
makes an angle of about 77 degrees relative to gravity. In a few seconds, the resultant vector
changes in magnitude and rotates relative to the pilot's head. Because the head has not actually
rotated the semicircular canals do not signal a corresponding rotation. The absence of Vertical
semicircular canal input combined with Uie dynamic otoUth input produces a forward velocity
sensation and less perceived nose-up attitude than would be predicted from the 77-degree
change in the direction of the resultant vector.;
A second circumstance in which judgments of vertical are apt to depart from alignment wiA
the existing force field occurs in the presence of a structured visual field. A promment visual
frame of reference with Unear dimensions tUt^d relative to the direction of the existing force
field will frequently produce a compromte: estimate of the vertical between visual and
forpe-field cues. It appears that some individuals are relatively more influenced by visual
reference, whereas others may be more force-field oriented, and there has been some mterest m
exploring the impUcations of such differences for aeronautical adaptability (Brictson, 1975).
FUght conditions giving rise to misleading visual reference wiU be discussed briefly m a later
section.
Judgments of vertical may also depart from aUgnment with the resultant force field when
the magnitude of the force differs substantially from the customary 1.0 g field. Systematic
departures which appear to be attributable to differences in otoUth displacement during static
tilt in "hyper-g" fields have been observed (for an overview cf. Guedry, 1974, pp. 96-103).
Illusions Associated With Head Movements
NuttaU (1958) attributed a series of fatal aircraft accidents to pilots' head movements
required by the necessity to shift radio frequencies during procedural turning maneuvers at low
altitudes. Several iUusory effects can be eHcifeed by head movements during such turmng
maneuvers.
3-29
U.S. Naval Blight Surgeon's Manual
Acituai Attitude during
CataMt Launch
Predicted
Pitch-Up lltusion
Perceived
Pitch-Up Illusion
Figure 3-10. Actual aircraft attitude, predicted pitch-up illusion,
and perceived pitch-up illusion during a catapult launch.
3-30
The Cross-Coupling CorioUs Illusion. When an airi»J(ft tdtdtis at some angular velocity
about one axis while the pilot'« KiS-M abotll^^
t02, the head uiidergo^ i^^lar tefer^tiiatt^^ magnitude, oji 0^3, about a third axis,
orthd^OnH te^e other t*o axes. A specific exatfiple wiU serve to clarify the effects that such a
stimulus produces. Assume that an observer, on a turntable which has been rotating in
counterclockwise direction at constant velocity (coi) of 60 deg./sec. for 20 or 30 seconds, has
his head fixed in tilted position toward his left shoulder. If he then movei' Ws ^A'Wui^t
position, he experiences a forward tumble and a sUght lettw'ard rotation. ¥^iEttsiW^iy^us
produced by the canal stimulus is primaity doito («lAiye) and slightly to the left. Aji
iWporfttt pom* to ttote^re is Hm just after the head is upright, the otolith system would
signal the true head position relative to gravity, yet the fairly strong residual effects from the
stimulus to the vertical canals give a sensation of forward tumble, i.e., a perceived attitude
change of the body and entire vehicle relative to Earth- vertical. Here, then, is a ituatom
which accurate information provided by Ae otoUths regarding orientation relative ttt the 1^
is dotiipromised by misleading cattal signals, resultiug to^att mxmtf change in attitude. The
perfeeptiort is coAl#te| «ftd disturbing, probably because of the intravestibular conflict, but
sU^tM^ ^rronebiii ehaU^eito attitude are reported (Clark & Stewart, 1967; CoUins, 1968).
This effect is sometimes referred to as a Corioffi eff^sfe* because the inertial torque Which
stimulates each canal can be deiffved by integrating the cdmfonentfe of the lineal Gdtfelifl
^teratioft wWtelt act fa aJS^iment wi* «e catfal Wallaittom a practical point of view, the
conditions tei control flietK^tude of this disturbing effect in aviation are the total angle
through which the head is turned (the greater the angle, the greater the total integrated
stimulus), the angular velocity (wi ) of the aircraft, and time elapsed since onset of vehicle turn.
Head movements made during the angular acceleration #M^h «)mmencBS a turn are not
disturbing because the effects of vehicuhir angular acceleration combine with the cross-coupled
(coi C02) angular acceleration to produce a total semicircular canal stimulus which ns nrf
disorienting or nauseogenic (Guedry & Benson, 1970i*.
f>:'.j
Aircraft in a bank and turn commonly do not have a very high angular velocity (^i). Under
these conditions, the magnitude of cross-coupled (Coriolis) effects from head movetoenttWOuW
be relatively slight, but, in the unstable conditions, of flight, even dightly disorienting effecto
could be dangerous, if external visual reference is either absent OP. misleading. In higher rate
sustained turns, these effects can be strong, and since they may also induce physiological changes
conducive to vasovagal syncope, it is not only disorientation but also a possibiUty of reduced
g-tolerance which could affect the pHot (Sinha, 1968).
3-31
U.S. Naval Fli^t Suigeon's Manual
m "S^em-Mushn, There is another effect during head movements in aircraft which is
apt to occur whenever the aircraft k m^img m ahnonnal force field. This effect was
observed during coordinated 2.0 g turns about a large radius (r) of several iniles. In m
maneuver, the aircraft speed (tangential Unear velocity) k very high, but the angular vclodty
(oji) IS very low, about 4 deg./sec. or .07 rad./sec. The center of turn may be at a radial distance
of one or two mfles fro^ the mmait. The 2-g resultant is obtained by resolving the gravity
vectoft Willi the centripetal vector (£.,2,). To calculate centripetal acceleration, c^i must be
expressed m radian units. The low angular veloe% means that fte qross^oupling (CorioUs)
effects described in the preceding paragraphs would be almost ne^igible. Yet, during head
movements in such turns, observers reported experiencing peculiar sensations sometimes
mvolving sudden shifts in the apparent attitude of the aircraft, together with nausea which
would undoubtedly cubninate in sickness in some individuals if frequent head movements were
made in tWt s^iation. This has been caDed a "g-excess effect" because sensory signals from the
otohth system fs^i^ the head hmmed in a high-g field w^d exeBed .iiose produced by the
same head movement in a 1.0 g field. The extra otolith input may be percfpttjally attributed to
a sudden maneuver of the aircraft, in which case a change in aircraft mm^m the plane of the
head movement would be experienced. The perceived attitude change would be at right angles
to the cross-coupled (Coriolis) effects. Tliis is comparable to the effects of force-field magnitude
on . mimmm of verticality described previoilgly, excep* &at head movement introduces a
dynamic stimulus to the otoKtii system, and the perception is more confusing and hm
consistently reported (Gilson, Guedry, Hixson, & Niven, 1973). Note also that head movements
m weightless states are also nauseogenic and disorienting (Graybiel, MiUer, & Homick, 1974)
Whfle this phenomenon is not completely understood, it could be an example of intrave'stibular
con«c^. 1^., the head movements induce normal semicircular canal responses unaccompanied
by the usual otplitMc and proprioceptive feedback.
Fre88ure,(^teniobaric) Vertigo
Pilots sometimes experience strong, sudden vertigo involvittg' fe^fieM of Spinning, rolling,
or tilting, and nystagmus sufficient to blur vision during or soon after ascent or descent. The'
pflot may feel his ears clear suddenly (sometimes a hissing sound is reported) and
simultaneously experience strong vertigo. In one case, a member of one of the famous military
a^Atic m^^mm^vm m afflicted Portly after landing that for several mimites he was
unable to wdk fftfte Ms, plane to join his fellow team ffieinbers who were being greeted by
waiting dignitaries. Surveys (Lundgren & Matorl96g; «*ill»|dtteSi -19Sf) have indicated that
from 10 to 17 percent of pilots experience pressure vertigo at onfe ttitg ^ Mother. UsuaUy the
vertigo is transient, 10 to 15 seconds.^but it may last much longer.
3-32
Vestibular Function
Pressure vertigo is vestibular in origin, but its exact mechanism is not understood. Even slow
changes in ambient pressure can produce symptoms in some individuals. It is also sometimes
induced by the Valsalva maneuver. High forcing pre8ffll|gs f^'#p©|ingA6 eaM^hiaii t^e m
one side, i.e., asymetry in ^emmyf^mi&S^fmm h U mmmon in individuals who
experience f»es8^ y*^,.8Hd experimental studies (Tjemstrom, 1974) indicate that some
individuals are much more, susceptible to this form of vertigo than others. Aside from dangers
associated with barotrauma, the strength of some attacks of pressure vertigo mditate against
flpfig with any condition which threatens pressure equalization in the mi«» te*i
There has fee^n some indiMtioWL iii* hi#i-tevel soiftidv Wt^rtei «d repetitive, and
infrasound can also oecasionany iiidti*e ve8«lmh» «irtoces .^CParl(^»<Mite, Tubbs, &
Wood, 1976). • ' ,
Disorientation Not Athj^toUs to Strong Vertiliular Stimuli - Primacy of Vision
Stew of ^ disorienting e0t««Bi-d«^^ id-previous sections would be considerably
ameliorated or overcome by good visual reference to the Earth's surface. The single most
important cause of pilot disorientation is the absence of adequate visual reference to the Earth
because of darkness or adverse weather conditions. Certain flying conditions can mtreduce
visual information that may be either directly disorienting or misinterprete^^.iNift thf' CO*cial
factor in the human response is that, witot#>9^ visual ref«riince^ th#r«afcto fiU4<ace, the
t^mmm ^nm^ spa^rtxifeoM^tion a^. ^Qt sufficiently reliable to permit safe
piloting of a4t«r*&.m was nicely dei^oiistrated by Krause (1959) who measured times from
occlusion of pilots' visual reference until the aircraft assumed a condition requirmg 10,000 feet
for recovery. FoUowing banks and turns, times were typicaUy 20 to 30 seconds, but even after
level f1 '■ t mean times were on the order of 60 seconds. Many instances of pUot disonentatjon
are less at^ibutable to some overwhehning mislea<Mwt>i«S#ula|i W»^S«btte
perceptual inconsistency or wen to pemeptualinsenaitiyity to flie acceleratio»fftvWWm«%
Autogyral and Autokinetic Illusions , .
It is weU known that a small, single, stationary K^t Jn an otherwise dark room will appear
to move in a more or less random path, and that the direction and extent^ oi«^pafWt W0»emeBt
can be influenced by suggestion or th^ fixpectMlotl pf a stationary ohseryer, A number of m-
stances in which pilots have mistaken stars and othei fixed light sources as moving aircraft have
probably involved this "autokinetic" effect (Benson, 1965). Perhaps less weU known is the fact
that individuals in a rotatable but stationary structure frequently perceive rotation of the entire
structure This "autogyral" effect occurs in darkness or in ffluMUnated but enclosed devices. Ab-
sence of specific motion cues does not insure perceived stabiEty when motion expectations are
high.
3-33
U.S. Naval Flight Surgeon's Manual
Perception of Tilt
: (tjrpicaUy, mean judgments of verticality indicated by psychophysical studies suggest fairly
aecnifete pe^^. the yange of judgments usually includes a few large errors even though
an obsei^er '^tt devote his entire attention to thi» one task. In long flights whem vibration and a
number of momentary accelerations feomut«iidtotJe i»w« demand correctiTe re^^O^
the pilot, the threshold of corrective responses to vestibular stirauK may be raised by the
"acceleration noise level." Perceptual errors may then approach the occasional extreme errors
encountered in lai®f atory experiments and also those found in water immersion studies where
very large errors in the perceived vertical have been noted (cf. Guedry, 1974, pp. 88-92) Even
without a background trf-Haeeeleratiiim noise" or water immersion, there are large mean errors in
estimates of verticality when tilts occur very slowly. For example, pitch and/or roll attitudes of
ten degrees are typicaHy regarded as upright, whereas sensitivity to detection of slow tilt
mcreases substantiaUy if the subject is rotated about the axis that is being tilted (Benson, Diaz,
& Farru^a, 1975). Very slow or sustained tilts diminish rate information from the otoHths and
corroborative iiifWmation from the semicircular canals, 'md 'flm^ increase the likelihood of
adaptation effects (see iffief MetSon dn the iefi§®fy t^^^ motion I ihtb coded
neural messages). • •
In flight, a ^adual roU or pitch away from straight and level flight sometimes occurs at rates
hetew the sevAkmrn^mmt Molith threshold perceptual levels. Adaptation can make a tilted
p«IHa««tt aitete'Ji^P^. iii tfiat return to upright may yield a definite sensation of tilt in the
opposite du-ection (Passey & Guedry, im)M k l^f^owly entered a coordinated bank and
turn, alignment of the resultant vector with the head-to-seat a3t& mteM aUoiv for stiU further
undetected deviation from straight and level flight. If the pUot should then become aware of the
aircraft attitude from instrument information or external reference, his corrective actions could
iHtt^diaeg f8ttibil&*-stimuli considerably above threshold levels, indicaHng a definite change
frdifi an attitSia#W»i<*lfl#ja8t befen per^^^te^straight and level. Circumstances such as these
produce "the leans," one &f tfee mm commott forms of disorrentation reported by pdots
(Clark, 1971). The cockpit instruments show that the aircraft is straight and level, yet the pilot
feels that he is in a bank and turn. Though the pilot may be able to fly successfuUy by his
instruments, prolonged perceptual conflicts can eventuaUy degrade his performance. Curiously
^^m%m'^ niarpr^t for 30 or more, much longer than predictable after-responses ;f
the vestibfllkf lystem. It is as th6^^ c^ncg^tiie percei^gt 'Vertl^ igiKsplace^ from the initial
non-compeUing sensory information about upright, then th^ dyi»Iae#d lierGeption inay sustain
Itself until the pilot attends for awhile to some other aspect of the flight task, orUnfflfee fe a
good visual reference to the Earth (Benson & Burchard, 1973). Emotional dkM^amSm hwf
ftmher degrade "position sense." ' ' ' ' 'i
3-34
Visual Stimuli aitid Oisojientatioii
Considering the range of positions which may be judged to be vertical in the absence of
clearly misleading information, it should not be surprising lhat "the leans" could also be
provoked by misleading visual stimub, such as sloping cloud banks, slanting rays of sunlight
through clouds, rows of hghta erroneously beUeved to be hoilzioiltal, tod ^en the edge of the
instrument ^are-ahieia slopirig over the attitude gyro (Figute S-H). Pilots occasionally find
iiemselves in aewrly inverted flight when just prior to the discovery they had believed
themselves to be in normal level flight. The probability of this kind of error is enhanced by the
fact that man's estimates of vertical are relatively poor in some tilt positions and especially
when he is inverted (Graybiel & Clark, 1962). hi these positions, visual cues assume a more
predominant role (Young, 1973), . Ni v \ i . '■■
\ I ^ I ^> j "
Erroneous perception of aircraft attitudes can r^lt ittl ertofteous perception of aircar^ft
altitude. A pilot; whosi JBuperiEft is iri n6^^ki|h^tude ?nay, on viewing grtond lights in hfe line
of ffl^t, believ^fhis ai^tud« to be considerably greftter than it is because of the downward mgle
of his view of the Ughts. Similarly, a pilot flying over water with his port wing high may, on
viewing shore hghts on his port side at an approximately known distance, again considerably
overestimate his altitude if he is unaware of the aircraft attitude (Cocquyt, 1953).
Visual effects at!~i^~ |flteai~r^-lfe-^ttge~ei^itBalK~"p®l|eptioii of atfltude
(Benson, 1965; Melvill Jones, 1957). At high altitude, the horizon is depressed with respect to
the true horizontal so that orientation of the aircraft to this false reference may resuU in the
aircraft being flown witli one wing low or with a nose-down attitude. The magnitude of this
error is not large, being about four degrees at 50,000 ft., but confusion can occut when the pilot
looks out on the other side and finds that he is flying wing-Iii#i with j^es^ct to the visible
horizon on th# lftde. I '
Another illusion resulting from high altitude has been observed in which the pilot looks out
from the aircraft and sees the moon and stars below the apparent horizontal. From this, he
presumes that the aircraft must be flying in a banked or even inverted attitujle. A number of
pilots have madfe control movements to hjong tl^^sk^l^feack ip what| th|f thought was a
normal attitude, before closer attention to th^instnime^tej'eve4ed thej erroneous nature of
the visual petfiept (MelviU Jones, 1957). ^' mm3m situation m|y occur in the prolonged
low-altitude circling involved in ASW maneuvers. As indicated earher, a sustained, coordinated
bank and turn can easily be perceived as straight and level flight. If this occurs, a view from
wing-high wide of the aircraft could place the moon and stars considerably below fte
erroneously perceived horizontal (Figure 3-12), possibly leadilig to the same kind of control
errors reported by MelviU Jones in high-altitude fli^t.
AtiituieGyft} . , Attitude Gyro with Glard Shield
irt.S6i^i(h|ana Level Flight , - Form ing Artificial Horizon
F%i»e 3-11, A potential false horizon illusioit^poaB^tt by MstAaient ^are shield (Tormes & Guedry , 1975).
fnl^eAl^jp^^mB^oa oi Aviation, Spat^
c
o
Viestilnilar Ftonetfoil
Figure 3-12. In a coordinated bank and turn, the pilot may see the moon and stars below the
apparent horizontal. This can prodiice a momentary illusion of nearly inverted fli^t and lead to
erroneous control litoVeAtaritS.
Dynamic Visual Stimulation ,
Large moving visual fields (visual angle greater than 30 degrees) can it|4wy||ihe sensation of
body motion within firee seconds and abo suhstanliai sensations of body tilt (Ufaiidt,
Dichgana, & Koenig, 1973; Brandt, Wist, & Dichgans, 1971; Dichgans, Held, Young, &
Brandt, 1972). Of considerable interest are apparently related findings that large moving visual
fields modulate neural activity in the vestibular nuclei even when the head and body remain
stationary (Dichgans, Schmidt, & Graf, 1973; Young & Finley, 1974). In lower animals,
vestibular stimulation modulates responses in central visual projection fields even when the
retinal image is fixed (Bisti, Maffei, & Piccotino, 1974; Griisser & Griisser-Koraehls, 1972; Horn,
Steckler, & Hill, 1972). These various results jpdaiit t© tte inteate iftllMt^^^
and vestibular systems in both the "feed forward" and "feedback" loops involved in iie control
of whole-body motion.
r
In aviation, either a large tilted frame of reference from cloud formations, etc., or uniform
motion in the p^ot^ visual field can induce illusory perceptions of the attitude and motion of
the aircraft. Such effects could influence the pilot in high-speed, low-level flight, or in any of
several situations. A visually induced illusion appears to have been important in the following
disorientation accident involving loss of an aircraft. Toward the end of a long day of flying, a
student pilot was flying on the starboard wing of his instructor's aircrrft. The student's view was
fixed on the instructor's aircraft, and because of this formation, his line of sight was turned
dniost 90 degrees to the Mnfe of flight as thejf dtondfed fictf 8©m« time tiirough heavy mist and
layered clouds. The unidirectional streaming of the peripheral visual field was therefore almost
ideal for inducing sensations of whole-body turning to the ri^t. As the student shifted his
3-37
U.S. Naval EHglit Suigeon's Manual
attention to his cockpit instruments, he experienced a strong illusory sensation of right bank
and turn, although he was in fact in level flight. Following an erroneous corrective action based
upon his false perception, the student, now at fairly low altitude, ejected from his aircraft.
Contributing to this unfortunate incident were a number of factors. The conditions were
adequate tQ' set up a normal illusory reaction to an unu^al niotion condition: The pilot had
just transitioned from an external reference to instrument fli^t; the pilot was relatively
inexperienced and fatigued; altitude and proximity of another aircraft provided little time for
corrective actiojis. ,
Flicker Vertigo
Flashing hght from sun rays or shadows reflecting from hehcopter rotors or from blades of
propeller- driven, fixed-wing aircraft can be very disconcerting, and, in exceptional cases,
epileptiform seizures have resulted. In prop planes, the phenomenon may lie strongest while the
aircraft is taxiing into the sun so that the blades are rotating at relatively low rpm, and intense
light flashes may be reflected into the eyes. In a helicopter survey, 35 percent of the pilots
responding reported disturbance by flicker from rotors, but 70 percent reported difficulties
arising from reflections from the anticollision light (Tormes & Guedry, 1975).
Perception of Vertical Linear Acceleration
Misjudgmettt of heUaOpter motion during hover was found to be a prominent factor in a
number of c^orbntation incidents during conditions of poor external viability. Moreover,
extraneous motion stimuli such as a visible "salt" spray through rotor blades, wave motion^ ^p
motion during night landings, and even wind currents in the cockpit can exacerbate the
situation in naval hehcopter operations (Tormes & Guedry, 1975).
Vertical linear osciUations introduce linear accelerations that are aligned with gravity so that
the magnitude of the resultant force field changes relative to the head, but its direction does
not. If an erect observer is osdUated vertically , the- changing linear acceleration is approximately
perpendicular t^ jfee utricular otolith plane, and, therefore, it is ineffective aa a utricular
stimulus. Its approximate alignment with the saccular otohtiiic plane would introduce an
effective saccular "shear" stimulus, but the saccular otohths, already deflected by a 1 g shear
force, may be relatively insensitive to added acceleration in the same plane. From this
theoretical point of view, otolithic insensitivity to vertical linear oscillation (YLO) as compared
with its senativity to horizontal linear oscfllation (HLO) mi^t be expected. Yon Bekesy (1940)
reported accurate amplitude estimates of high frequency (up to 4 Hz), small amplitude VLO,
but his stimuU involved high peak accelerations at frequencies where otoUth gain may be high.
Recent neurophysiological findings (Fernandez & Goldberg, 1976) do not support the idea that
otolitilic neural input informatioTl would fimit perception of VLO as opposed to HLO, but some
3-38
perceptual data sa^t -tiiaib ipefift^fiwaaicicficiencies may occur with low-frequency stimuli.
Walsh (1964) reported higher thresholds for 0.11 Hz VLO than he had previously reported
(1961a, 1961b, 1962) for HLO, although his data are not entirely consistent (cf . Benson et
al., 1975). Several recent experiments (Malcolm & Melvill Jones, 1974; Melvill Jones, Rolph, &
Downing, 1974-1976) have indicated perceptual inaccuracies^ with f S0''tital*lsi# '^«issive
relative to fairly accurate percepti«ts#«@£(il*diift*lhi««P#«®dl^&^^^^ Young &
Meiry, i9^.' WidiACI|J^)it *lttmulu8-^^ phase errors (individuals
ejeperienced maximum downward travel during upward travel) at 0.11 Hz and zero phase error
at 1.0 Hz. Other phase data (MelviU Jones et al., 1974-1976; Young & Meiry, 1968) for HLO
and VLO are not consistent with Walsh (1962, 1964), probably due to differences in reporting
methodology and in high-frequency stimulus artifacts. However, the averaged oculomotor
responses of MelviU Jones et al. (1974-1976) exhibited stimulus-response phase angles at
0.11 Hz and 1 ttz, cd'ri^leM' with Walsh's subjective data. Differences in body position
(reclining in Walsh's studies, erect in other studies) may also contribute to some of the
inter-experiment differences. Spinovestibular interactions may modulate perceptual experience
in the erect observer during VLO through mechanisms similar to those involved in the very
different perceptual experiences noted above in the aftereffects of actii)e^is§lphmve ftiming.
The presence of substantial perceptual phase errors and even the inconsistencies within and
between studies are relevant to the problems of aviators, especiaUy pUots of helicopter and
V/STOL aircraft. If methodological differences and stimulus artifa^'feftrtmce perc^Hud
consistency in formal experi|it^tl«iA#t
and occasional large phase ejrors iitAfitM?^ acceleration ei^yirpiuaent of
v^ously occj^pj^4;writh_ dtfferent elfweiJil^^^^, flight task.
i,t#,'pgrcip|{|#Mon»sten;die8
itft where he is
Prevention of Disorientation
Disorientation in flight wiU be experienced at one time or another by all pilots who fly more
than a few hours under e^mittoK^' of fOor vlibihty. However/tte &^n^''Q«e e#erience,
the ease with which it tb resdM, and Uie-^feqtlgH^' may be aware of
disorientation on every flight while others are^My troubled (Aitken, 1962). About 58 percent
of the helicopter pilots questioned by Tormes and Guedry (1975) indicated one or more
episodes of severe disorientation. It is therefore important to provide information and training
on means and methods of avoiding disorientation, of overcoming it when it occurs, and of
reducing residual anxieties resulting from disorienting experiences.
Aircrew fcitmction on Causes of Disorientation (cf. Benson, 1974b)
It is important that aircrew know
1. that disorientation is a normal reaction to a number of unusual conditions of motion
that occur in fhght
3-39
U.S. Naval Pli^t Surgeon's Manual
^ ^FmmlS0 '0i jJktmrf femepiom that are apt to occur in flight
3. the flight conditions and msiddiy^ lifcdy to jprodtic^'dfeogieafatityil
4. how to cope ij(7ih !^soiientatiott.,'
Navy pilots receive indoctrination on aspects of all of diese points in the course of their
trpWBg, te femind^s are rasscessary. Material presented earlier in this chapter will assist the
M^tSurgeon in amplifying on Points 1 and 2. The following is atiseful ehecMist for reviewing
factors which constitute disorientation threats to the awator in a helicopter oi m fixed-wing
aircraft:
1. Flight Environment
a- IFR - in particular, the transfer from external visual to instrument cues
J b. Night ground/sky confusion. Isolated light sources enhance the probahility of
oculogravic, oculogyral, and autokinetic illusions.
c. High Altitude - false horizontal reference. Dissociative sensations of detachment or
remoteness from aircraft, from Earth, or from reahty (break-off phenomenon).
"Break-off" may occur in helicopter pilots at lower altitudes or on crossing
escarpment.
d. Fhght Oves Featureleis Terrain - false perception of hei^t
2. -Fli^t Maneuvers
a. IVolbnged acceleration and deceleration in hue of fh^t and catapult
launches — somatogravic and oculogravic illusions
h. Prolonged angular motion - sustauied motion not sensed; somatogyral illusions on
recovery; no sensation of bank during coordinated turn; cross-coupled and "g-excess"
illusions if head movement is made while turning
c. Subthreshold changes in attitude - "the leans" induced on recovery
,,4- Workload of flight maneuvers - High arousal enhances disorientation and reduces
the abihty to resolve peeceptuttl conflict.
e. Ascent or descent — pressure vertigo
f. Cloud penetration - VFR/IFR transfer and attendant problems especially when
flying in formation or on breaking formation. In the "lean on the sun" illusion a
bright spot in the cloud may be interpreted as up. Depending upon the heading of
the aircraft relative to the bright spot, the false vertical reference may induce
attitude errors in roll or pitch.
B» Aircraft Factors
a. Inadequate instruments
3^0
- I
c. VifflhiHty of fegtroflii^ • v ••-liif.ru. . . . ' ' i
d. Ba#y positioned displays and cpnti^ote head, moveinent re<pwe|l to sep; and
operate
e. High rates of angular and linear acceleration, high maneuverability
f. View from cockpit - Lack of visible aircraft structure enhances "break-off" and
provides a poor visual frame of reference. - ' ' ',! t-" -.**" -
,,, , nib !-ir.> I it - 1; i ■ 'i.. j ^n V n-/*-.-, ..
4. Aircrew Factors . . k.l
a. Flight experience
b. Training, experience, and proficiency in instrument flight
c. Currency of flying practice
d. Physical health - upper respiratory tract infection and "pressure vertigo"
e. Mental health - High arousal and anxiety increase susceptibility to disorientation.
f. Alcohol and drugs - impaired mental function. Alcohol and barbiturates, even at
low levels, impair ability to suppress nystagmus. .
g. Fatigue and/or task oveiioad.
I. .■•tsjir.iT >' 'r ^n:< . .n-1'.ol, •.niv tnj/'r : »m''Mi!»1i n. I.'. -VI ..- .»•... .
^ Cbnmms^ MMBSmrmi .0^ ionbif^.^^i^^ list of conditions leading to
disori^tation were derived fMi^iigUrvey of Navy helicopter disorientation incidents:
1 . Perception of the wind throu^ cockpit side window while in hover or translational lift
2. Flying into smoke flares vt,. ..,
I. 3. Tasli satuiition ; ,. . ,
'C'lfilfclteli'PP^Mai^^hile rotors engaged) at night
6^ Lbw-altitiide^search pattern at night
7. Night launch from forwsBfd spots on fli#it deck
8. Lack of recent instrtiment flying .h /.fl-u-,.
9. Relative immobilization by '^^'Mlft for prolonged periods
10. Communication difficulty (noise, poor radio discipline)
11. Excessive translational lift vibration
12. Hover not level ' '^""^f- "• ' '
13. Reflection of anticollision lights
1
mi
tl.S. Naval Hi^t Suigeon'e Manual
14. Vibration dampeners on instrument panel inadequate, allowing blurring of instruments
15. Lig^t from middle console reflects on middle windscreen
16. Cyclic stick not in center neutral position in level flight.
These lists of flight conditions and maneuvers that induce disorientation are helpful, but
^ey are certainly not all-inclusive. For example, maneuvers such as barrel rolls and Cuban eights
tiiat involve temporary inverted fli^t can induce epnfiision, At llie point of inversion, the pilot
tends to move his controls in the wrong direction for completing Ihe maneuver. The interested
Flight Surgeon can develop a substantial catalog of flight conditions that tend to induce
disorientation by dialogue with pilots. Pilots are frequentiy interested in describing their
experiences and also their methods of resolving problems with disorientation. '
Aircraft Factors. It is important to remember that there are factors peculiar to «ach aircraft
which can conti^bute to disorientation. For this reason, FH^t Surgeons should be alert to these
factors in discussions with pilots because knowledge of conditions pecuUar to a given aircraft
may be useful information for general dissemination to the squadron and may also be helpful in
understanding problems reported by individuals.
Aircrem Factors. Surveys have shown that flight experience does not prevent disorientation
(Moser, 1969; Nuiow, Cunidngham, & Radcliffe, 1972), but the indidmce<appears to be reduced
with increasing experience. Current flying practice is helpful in several ways. A number of
studies of repeated exposure to unusual motion have shown that both disturbance and
contraproductive reflexive actions are diminished and/or modified in a productive direction as a
result of repetitive experience with unusual motions (Guedry & Correia, in press). It is not
unlikely that disruptive perceptual-motor reflexive responses diminish and itt their modified
form are useful to the pilot at a subconscious level in providing the feel of fl^te.maneuvers.
Something like this is needed to account for the fact that highly experienced pilots, ^&.hi^y
disturbed, whereas the novice is not, by fixed-base simulators hi which the visual scene moves in
response to control action.
Instrummt skills are highly dependent upon practice. Interpretation of instrument
information is an intellectual function which demands inte^ating .lymbQUc orientation cues
from some instrument with digital information from others. Recentiy, there have been efforts
to make use of the strong perceptual effects of large moving visual displays
(cf. Dichganset al., 1972) to combat "the leans." Servo-driven artificial horizons subtending a
160 degree arc can be projected onto aircraft instrument panels, and they appear to be more
compelKng fJian information intellectually derived from the usual, small aircraft instruments
(Malcolm, Money, & Anderson, 1975). However, with current aircraft instruments, the
342
Vestibular Function
information provided may be far less compelling thi0i"'#i®'dii'ect perceptual respons^to iome
unosual ffight conditions. Yet, the pilot must use the intellectually derived ifiltefiii^HtifroM hSs
U3SteWiaej?t8.^.By the lim© instaaunent scan information becomes secon4,ni||ttl5|^-^§ pilot may be
unaware of many disorienting sensations because his control actions may be overriding these
sensations, and he is also highly prolicieiit in the use of his instruments. The out-of-practice,
"experienced" pUot may have partially lost both of these advantages and may be more at risk
than the novice if he is overconfident a3i3 etdSk ifiPe'SteMing flight c'Dii&5w^J%r^(isreaBom,
refresher training in the form of leetare m^teria^^fteteiWiWflgiilr Sli^ to
resuming operational flights is desirable. Some experienced pdots may feel they are immune to
disorientation, but exposure to a simple, ground-based motion device is ordinarily sufficient to
remind the aviator that he is, in fact, not immune. The pilot vdth many flying hours will have
learned much about disorientation and coping with it, but the causes of disorientation are so
numerous that he is unlikely to haf#%ad eTiip®H»tteeNv!iifevery type, fte^nresv^rtigo may occur
only one time, but awareness o;^ its potential effects may be sufficient to CcMip th(|.{iiil0t t^th a
cold to avoid %iiig, ot p §jiekhM^ plflit who experiences it to remain sufficiently calm
enough to eombat it. Thus, knowledge of conditions that increase the probability of
disorientation can serve to avoid it and also serve to reduce debilitating hyperarousal when and
if it occurs. Lecture material presented as part of a ground-based demonstration of normal
disorientation expei-iences has been receivfed!''wl#i^iftQMK^'by expert%ft(5«5t' a8''well as
beginning aviators (Benson, persond cott'totii!
• ■ ■ ■ - i I, ■ ■
Aircrew Instruction on Prevention and Coping with Disorientation
' Although knowledge of cohdittons #^|n^odhce disorieHta#dtt'il iinpbil«at to aircrew, they
should never hear about the illusions occurring in flight and the consequences of disorientation
without also hearing the instructions for how to deal with the problem. In this connection,
several articles (Benson, 1974b; Benson & Burchard, 1973) have hsted practical advice to
aircrew for preventing and coping with disorientation.
How To Prevent Disorientation. ^
1. Reffiaiti ctftt^ced AW you cannot fly by the "seat of the pants."
'2. Do not allow control of the aircraft to be based at any time on "seat of the pants"
sensations, even when temporarily deprived of visual cuep.
3, Do not unnecessarily mix flying by instruments with flying by extetnid visual c^eg.
Mn td mate an feMy iiaflSition to instruments when flying in poor visibiHty, etc.; once
established, stay on instruments untiluse of external cues is clearly practical.
5. Maintdn hi|^ proficiency aflidpmtii^e in fl|i^ » i
3-43
U.S. Naval Mi^t Sui^Qii's Manual
6 . AmM uimeceesary iroaaeiWePs of aji^rffE mv head movement which are known to indupe
dkedentajtioni.
7. B^'^d#ailafl?f 'vilpftnt itf^^^ sttuaftions, such as at ni^t or in foul weather, in
order ta fti^^tfik &tt!lecWtf coiiimaiid flie ibrientation and positiettl bf the aSt6raft.
8. Do not fly with an upper respiratbty teaet infection, when under the influence of drugs
or alcohol, or when mentally or physically debilitated.
9. Remeinber, experience does not make you immune.
How To Cope With Disorientation.
• 1. Persistent minor disorientation (e.g., the leans) may be dispelled by making a positive
'.> effort to redirect attention to other aspects of the flying task; a quick shake of the head,
• m:, ^imm^^ aaxms^ft is ^a^tand level, is icifeetive with some pilots.
WHten" 'sdddenfy cdUirdhlill by strohg ittiisdty s'erisa^one or when experiencing
■ ■ ^fiBolMeg in" estilbljshillg 'o^etttation and control of the aircraft, follow these
' procedures;
a. Get onto instrumeiitl', check and cross-check. Insure good instrument illuminatiQn.
b. Maintaia instrDtn^ reference. Control the aircraft in order to make the instruments
display the desired flight configuration. Do not attempt to mix flight by external
visual references with instrument flight until external visual cues are clearly
practical.
c. Maintain correct instrument scan; do not omit altimeter.
d. Use advance headwork on necessary control actions in those maneuvers that
typically produce confiision (e.g., inverted position in barrel roll).
e. Seek help if severe disorientation persists. Hand over to copUot (if present), call
; ground controller and other aircraft, check altimeter.
f . If control cannot be regained, abandon aircraft.
3. Remember: Nearly all disorientation is a normal response to the unnatural environment
of flight. If you have been alarmed by a flight incident, discuss it with colleagues,
including your medical officer or FUght Surgeon. Your experiences will probably not be
as unusud as you thought.
Additional Information for Helicopter Crews. A Hst for avoiding and coping with
disorientation in heUcopters (Tormes & Guedry, 1975) was essentially a duphcate of the above
except for the following items: . '
1 . When disorientalion occurs, fly strai^t and level and inbfease forward fflrspeed.
3-44
■ y^til»iil«r Function
2.
3.
4.
5.
In weather, tuiii off the forward rotator beacon.
Always fly with a trimmed stick (i.e., aircraft flies level with stick neutralized).
Whieii ^I^^SLtfttipn Qcqp
Upon entry into a cloud bai^ luio
p«a|iW|^^air^eed.
I '. I
I--UF
Evaluation and Management of Disorientation Problems
Oae magor faefor in coping with disorientation is the pilot's ability to maintain composure
and intellectual command of the aircraft despite distractions and disorienting inputs.
Psychological disturbance is, therefore, one factor to be seriously considered by the Flight
Surgeon in pilots whose presenting symptom is disorientation (O'Connor, 1967). Impairment of
higlier mental function arid tike Teduc©i*»^ilP^^ frfe«fa«ntly accompany
health. Alcohol «ttd V^l]tf<^tlS drugs are additional threats to the effective resolution of
sH^Mfentation problems. To a surprising degree, they can reduce visual control of eye
movements in motion environments, while at the same time risking impairment of necessary
mtellectual control,
While probing for psychologic4 "Kb %h b,()S(^irs
indMduak wlio ^edence atroittg vertiginous episodes as a result of some pathological
condition are also frequently greatly disturbed by the experience. The emotional disturbance
may then lead to the conclusion by the doctor as well as by the patient's friends that the whole
episode is a sign of neurosis or an anxiety reaction. The same is true of the aviator who has had
an exceptional disorientation episode. Whatever tfxe actual cause of the disorientation, the
emotionid pv^P^!^ )feJ|tJ|fc0^ tpiresu
In handling such cases, it is important for the doctor to show that he is interested. This will
ordinarily be accomplished in the process of taking a history of the incident and relevant
background material. A thorough history is perhaps the most important step in the
examination.
. i Mm^mmmxy Im i^t^h^^mdj whether or not the occurrence of disorientation in a
pilot is due to a natural response to an unusual flight condition. The absence of similar reports
by others in the- aircraft does not by itself constitute evidence of an abnormal reaction from the
pilot. Crewmembers may have been equally disoriented without awareness of the fact because
awareness ^bmetimes depends upon checking the perceptual event against inf0miKitioll%0in#lte
instrument panel or from sudden VFli contact. - / .
345
U.S. Naval fli^t Siugepn's Manual
In attempting to relate disorientation to flight conditions, items in the check hsts should be
considered. When it appears that disorientation is attributable to normal reactions to either
aircraft or flight conditions, then reassurance that the reaction was normal, possibly including
discussion with other pflots, may be sufficient to allay anxiety. If concern persists, then a period
of dual fhgfef iffla^ se^Vfc f& reif6*e confidence, but it may be necessary to i^k thd Help* of a
specialist (cf. O'Connor, 1967). There is some evidence that acquired fear of some aspect of
flying in a previously confident aviator is amenable to treatment with a fairly high probability
of success (Goorney, 1973; O'Connor, Lister, & Rollins, 1973).
Organic causes of disorientalion are disctissed in chiqpter 8 on ptorlunolaryngology.
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Environmental Medicine, 1975, 46, 387-393.
Von Bekesy, G. Uber die starke der vibrationsempfindung und Aire objekiive messung, Sonderdkuck aus
"Akustisehe Zeits ", 1940, 3, 113-124.
Walsh, E.G. Role of the ve tibular apparatus in the perception of motion on the parallel swing. Journal of
Physiology (London), 1961a, 155, 506-513.
Walsh, E.G. Sensations aroused by rhytlimically repeated linear motion-phage relatioHghips. Journal of
Physiolo^ (London), I96lh, 155, 5SP'54¥.
Walsh, E.G. The perception of rliytlimically repeated linear motion in llie horizontal plane. British Joarnalx>f
Physiology, 1962, 53, 439-445.
Walsh, E.G. The perception of rhythmically repeated linear motion in the vertical plane. Quarterly Journal of
ExperiTaenfalPhystftlo^, 1964, 49, 58-65.
Young, L.R. On visual-vestibular interaction. In Fifth Symposium on "The Role of the Vestibular Organs in
Space Exploration " (NASA SP-314). Washington, D.C.: U.S. Goveriunent Printing Office, 1973.
Young, L.R., & Meiry, J.L, A revised dynamic otolith model. Aerospace Medicine, 1968, 39, 606-608.
3-50
)
I
c
CHAPTER 4
SPACE FLIGHT CONSIDERATIONS
Introduction
The Manned Flight Program for the 1980's
Functions of the Fhght Surgeon
The Physiology of Weightlessness
Bibliogiaphy
Introduction
The functions of a Flight Surgeon m supporting manned space fhght will be briefly
described, together with ^ S«ao«iary of the vehicles and miBsions et«it«Mpilatei lor &e 1980's.
Some relevant physiological findings of previous space programs will also be discussed. Detailed
treatments of these topics can be found in the bibliography provided.
The Manned Fli^t Program for the 1980V
■ the sira^e U.S. manned vehiele for the 1980's wiU be tibe Space Shuttle. The Shuttle
consists of three major parts: (1) the Orbiter, (2) the External Tank (ET), and (3) the SoUd
Rocket Boosters (SRB's). For launch, the two SRB's are bolted to each side of the ET, and the
Orbiter is attached to its upper surface. Launch is accomplished by simultaneous ignition of the
SRB's and the Orbiter's three main engines, the latter supplied with fuel and oxidizer by the ET.
The SRB's and ET are jettisoned prior to orbital insertion, which accomplished by smaller
engines on the Orbiter.
The Orbiter, shown in Figure 4-1 as it made its first free flight, is the crew- and
payload-carrying spacecraft. It is approximately the size of a DC-9 aircraft. It has a payload
capacity of about 64,000 pounds in a 15 x 60 foot payload bay and a maximum landing weight
of about 188,000 pounds. It can loiter in spaee for up to 30 days. The missions for which it is
designed include
1 . deployment and retrieval of unmanned satellites
2. deployment of sateUites with attached upper stages for boost into synchronous or
interplanetary orbits
4-1
U.S. Naval Flight Surgeon's Manual
Figure 4-1. Space Shuttle Urbiter "EintBiprise" competing ilS ijM ifeefe
flight in August 1977 (Photograph courtesy of Natioiml AeronauticB and
Space AdminiBtration).
3. operation of attached payloads. These may include instruments operated from the
Orbiter cockpit (such as telescopes) or experiments carried in a large manned enclosure
like Spac^liA, shown in Figure 4-2, which are conducted" hands-on by the Orbiter crew.
Some of the medically significant design features of Orbiter are:
1. Minimum crew is two, maximum seven. Figure 4-3 shows the OrMter mw Coinpartmeiit
where crew members work and hve for the period of a mission. ''{
2. Atmosphereisair at sea-level pressure (14.7 psi).
3. The radiation environment at expected orbital altitudes is benign (average crew dose less
ihitti one rad per mission).
4. LiHiiM^ accelerations are benign compared to previous programs (3 G maximum with
ahput 1 G^aegatite, eyebalfe-^up, component).
5. Beentry accelerations are also low in magnitude (nominaUy 1.6 G, 2.0 G maximum) but
longer in duration (20 minutes above 1.0 G) than those in previous space flighted Fof the
first time in space flight, the acceleration will he positive (eyeballg-down) rather than
transverse. These accelerations do represent a potential handicap to crew performance,
however, because the crew is in a cardiovascular deconditioned state as a result of
weightlessness, and the Orbiter is pilot-controUed to a power-off runway landing.
4-2
SHUTTLE
CORE
LABORATORY LABORATORY
EaUIPMENT ITEMS (El) EQUIPMENT UNITS [EUl
SCIENTIFIC
INSTRUMENTS
TOOLS
DATA MANAGEMENT
PART OF SPACELA8
SPECIMEN
HOLDING
CENTRIFUGE
SPACELAB
LABORATORY
EXPERIMENT UNIT
r
SU&SYSTEM SUPPORT
Figure 42. Spacdab laboratory showing Com«n Opetadons Reseaidi Equipment used for life sciences experimeniB
(Photograph courtesy of National Aeronautics and Space Adniimstration).
U.S. Navid Mi^t Sirt^ori's Manual
Figure 4-3. Crew compartment of the Space Shuttle Orbiter
photograph courtesy of National AeroitaotiCs aad Space Administration).
6. Extravehicular activity (EVA) capabiUty exists on aU flints. 1% space suit atmosphere
is 4 psi, 100 percent oxygen. A three-hour period of denitrogenation is required prior to
EVA to prevent dysbarism.
7. A rescue system designed for crew members of a disabled Orbiter involves extravehicular
transfer in a 34-inch diameter plastic sphere pressurized to 5 psi (Figure 4-4). The rescue
is passive, transfer being accomplished by a space-suited rescue crew member. This
equipment is mentioned Because it imposes physical, thermal, and pressure stresses upon
the crew.
Functtoiul oi the FT^ht Surgeon
Initial mediM inpmt to rnamied space flight, frequently involving inputs from Fhght
Surgeons, begins with specifying %aceeraft design parameters rdqilised for a habitable
environment. Launch and reentry acceleration vectors, noise environments, atmospheric
pressure, atmospheric composition, ambient temperature, food and hygiene systems, lighting,
radiation protection, work-rest cycles, cockpit layout, and many other design features require
continuous medical and human factors involvement in the design process.
4-4
Space Fli^t Gonsid«Tations
Figure 4-4. Rescue system for use with the Space lShattfe
(Photograph courtesy of Nattonfll Aeronautics and Space AdnuniBtration).
The basic functions of Flight Surgeons in the manned space flight program are similar to
their duties in aviation - certification of crew members for flight, health maintenance and
monitoring during flight, and treatment of illness or injury during flight or after recovery.
Certification for Flight
Hiere are three kinds of &0w podtions on the Shuttle. Their different duties cull for
somewhat different medical standards. The positions are
1 . Commander and Pilot - required to operate and conteol the vehicle throu^out all fli#it
phases and for EVA. These will be career astronauts. ;
2. Miidon Specialist - in dha^ei' of' itafload opert^ote in orbit; performs Orbiter
operations in support of payloads, iiiShiding EVA. Time will also be career astronauts
but need not be pilots.
3. Payload Specialist - in-flight expert in technical or scientific aspects of payload;
performs payload operations, but not EVA; does not operate Orbiter systems. This
individual is selected and certified on a flight-by-flight basis rather than as a career
astronaut.
4-5
U.S. Nmd Hi^t SuigeoM's Mmiual
The differences in medical standards between the first two categories are slight. Aviation
standards generaUy apply as to health and fitness. Better uncorrected visual acuity is required
tot the pilots than for the mission speciaUsts (20/70 versus 20/100). The limiting operational
factor for misdon specialists is EVA with fogged or displaced spectacles; visual acuity of 20/100
diould be satisfactory. The minimum height stajiiaraffdi- pfflots wiU be 64 inches. This is based
on cockpit reach and visibility requirements, not only for the spaceeraft, hut also for the
high-performance aircraft they will be required to fly. Height for mission specialists may be as
low as 60 inches; space suits wiU accommodate a 60-inch to 74-inch population. These standards
may be changed after experience has been gained in operating the Orbiter; indeed, more detailed
anthropometric standards such as sitting height, leg length, functional reach, and strength may
ultimately be required.
Since payload specialists are selected only for one flight at a time, their certification
standards can, in theory, be considerably relaxed. Defects or disorders which do not currently
impair capabihty, but might do so in the future, can be waived. Visual and auditory acuity
standards wiU be relaxed. There will be no specific age Kmitation. Conditions requiring
continuing treatment, or which might become acute during flight, wiU continue to be
disquaUfying. Some conditions, such as defective color vision, are interesting problems. The
Qfehiter being designed so that the abiUty to discriminate between red and green wiU not be
required of "passengers" (payload spfecialisls) even during emergency e&ttdilions. As far as
payload operation is concerned, the determination of the ^etaalist's quaKfieations may be left
to the discretion of the 8|i®nK>r of the paylaad. '■ . .
Female. applicantB will he accepted in , all categories fc^*w4ed Jhey meet She requirements,
including anthropometric standards. For actual flight, pre^ncy must be considered
contrauidicated until animal research demonstrates that no hazard exists to the fetus.
Detailed medical standards for aU Shuttle crew categories will be prepared by NASA in light
of the specifically proposed missions.
In-flight Health Maintenance and Medical Care
Maintenance of a healthy, productive space crew is now largely a matter of good planning
rather than extensive monitoring. Given a healthy crew at launch, and the relatively benign
environment of the Shuttle, real time monitoring is justifiable only for research or diagnostic
pm^oses. A few prohletti areas remain:
1. Motion sickness, although a self-hmited syndrome, can be a serious operational
drawback on short flights. Better prediction, better treatment, ,and possibly
development of desensitization routines for preflight use are needed. Clinical research
projects in this area will be necessary early in the program.
4-6
^ Space Fli^t ConddeTaftioiiB
2. The degree to which podtive reentry acceletatioM rt^i^tjirtlpentt^ A#pft)^®^ of
Shuttle crews is unknown. The G-forces are not liufB, but in view of the known
susceptibility of returning crews to postural hypotension and vertigo, a conservative
approach is indicated. Conventional G-suits will probably be worn, and some monitoring
accomplished, until the magnitude of the problem and its relationship to flight duration
are known.
3. As medical certification criteria are relaxed, especially for payload specialists, careful
monitoring of selected individuals may be indicated until eonfidenee is gained in their
ability to adapt to weightlessness without harm.
Health planning includes supervision of each flight's provisions for food, water, exercise (if
indicated), sleep, and protection against any mission-specific hazards such as radiation or
possible toxic contamination of the atmospherC IM' Wdrfe^'i^ ^ii^ ifc cBBpfel-iMHii ^lh'^'
crew, aAd it & beef doite by a Flight Surgeott^fedijciiy t«!ii^tea*d to flight and responsible
for the medical care of its crew. On some fl^ti, Jjrefii^t quarantine of thi« cfiew may be levied
(e.g., because no backup crew is available, and/or because a launch shp for crew illness would be
intolerable), and it will be the Flight Surgeon's duty to coordinate the quarantine program. He
should also be responsible for coordinating any medical research carried out on his crew and
; 1 assuring that it does not compromise crew health and safety. ^
Treatment of Illness or Injury During Flight
Plattdng for actual diagnosis and trefitmaat 'O* itt--fl;^i!#medW' probleias on
spacecraft and ciew me,, Wussion duration, and the ease with which ill crew members can-be
returned to the Earth surface. Typical Shuttle missions will be of short duration in a volume-
and crew -limited vehicle, with landing possible within several hours of a medical emergency.
Therefore, very limited diagnostic and treatment facihties will be provisioned. The object diould
be to provide emergency first aid, diagnosis to the «|E*e*lt of
and tiie capability to treat minor iUnesses or injurieSfl.ifMch,taffi^t o^C»l#ie terminati..^ lU^t.
The luxury of a physician aboard will be Umited. Good acquaintance of the FJi^t S«*gffi^teifiii
his crew and some practice in "telephone diagnosis" will be helpful.
The opposite extreme would be a large space station in geosynchronous orbit. Crew me
would be fairly large, with duty cycles of iOto 90 days, Mdl^tum to Earth would be difEcuM
and expensive. Therefore, a small orbiting hospital facility would be reqwed^-SKife one or two
health professionals onboard. Such a station is 10 to m fnm mny frxrai tMsiwriting, and much
remains to be learned about diagnosis and treatment in space. Both surgical procedures and
normal laboratory values, for example, will be considerably different.
4-7
U.S. Naval Hight Surgeon 's Manual
The i^t^^Uji has two problems to consider and plan for ~ "normal*' illnesses in
the age/seX' ppiak^omtof i»*hi^,the crew is a sample, and events pecuHar to space flight. The
first category encompasses trauma, dental emergencies, myocardial infarctions, abdominal
surgical emergencies, and possibly psychologica] problems, such as those seen in submarine
medicine. The second category includes explosive decompression, bends, hypoxia, radiation
injury, foreign bodies in the eye, and toxic Contaminants in the atmosphere. The last example
illustrates that a Flight Surgeon must be familiar with spacecraft systems and with any
potentially hazardous materials onboard as part of the payload. On biology missions with
various animal colonies aboard, it might be useful to have a veterinarian crewman available for
consultation.
P^fiejst^ in space are here tq siay. Their eiffe is largely a matter of applying famihar
priwoiplts to a distinctly unfamfliar enyironineiit mi remembering that syrnptoms and findings
are altered by weightlessness itself. In the ideal future, a short trip into orbit will be a
requirement for certification in aerospace medicine.
• The Physiology of Weightlessnegs
Medical and biological research into the effects of the weightlessness of space on living
organisms is in its infancy. We know what happens to healthy adult males in 84 davs, but we
don't know why. Hundreds of experiments suggest themselves: to determine how profound are
adaptations undergone by animals conceived and bom without gravity, and whether they are
reversible; to study these adaptations in progressively lower forms of life with presumably fewer
and fess specific anatomical adaptations to gravity, mch as flight of birds, swimming of fishes,
geotropism of plants and fungi, and so forth; to fly humans with diseases of gravity-^asitive
body systems, exploring the effects of disease upon adaptation and of weightlessness on the
natural history of the disease; and many others. In the middle of these experiments is the
crewman, who finds him or herself pressed intb the role of guinea pig, sometimes at the expense
of #pePaiiQftal efiKoiitfe^. The ffi^t Sitfgeon can help both the crew and the program by
remembering that the erew are patients first, and subjects second.
The most difficult aspect of constructing medical standards for space flight is attempting to
asise^ the possible interaction of weightlessness with pre-existing abnormalities in the crew.
Nothing is Certain in this area; speculation is possible based on what is now known about the
effects of weightieswfss on human physiology. For this purpose, and to assist the Flight
Surgeon in evaluating signs and symptoms reported during fli^t, a very brief review of these
effects is presented.
4-8
Space flight ConsiderationB
Vestibular Effects
The vestibular system presents both acute and chronic changes. The acute change ia in irtion
sickness, which has been present in about one-third of U«S. crewmen, with a range of severity
from transient nausea to repeated vomiting. Onset of symptoms is within a few hours of launch,
and duration is from several hours to about five days. Dextroamphetamine, 5 mg with
scopolamine 0.6 mg by mouth, has proven moderately effective as a palliative; the real
treatment is time and hmitation of activity. Hie cause is ttnfetiOTWIA. EesiftaUCft'or sasceptibiUty
to molffln sickness in normal or experimental 1 G enviromnents has not ^rpd^ted with its
appearance in fli^t. This is the only weightlessness-induced abnormality -w^Mch has required
medical treatment,
The chronic changes are twofold. First, a marked resistance to motion sickness
experimentally induced was present in all Skylab crewmen, even thosfe who had experienced it
at the beginning of flight. In the experimental situation, Ttit*igO and nystagmus after rotation
are present, but no autonomic symptoms (cold sweat, anorexia, nausea, etc.) appear. Second,
there is a marked subjective change in perception of the vertical. In the absence of giavity clues
to "up" and "down," an individual's frame of reference becomes totally body -oriented;
whatever way he is pointed is up. In darkness or with eyes closed, there is virtually no sense of
reference outside the body; tactile clues ar© inadequate, and locomotion within the spaeecSraft
becomes veiy difficulfe In geneual, ftm perceptual change has been an advantage ralAier thailiH.
handicap, however, since it permits an individual to feel upright no matter where he is woAiugi
Its proper understanding may shed some light on vestibular function.
Cardiovascular Effects
Upon entering the weightless state, an immediate, rapid, and massive shift of fluid from the
lower to the upper body occurs. This movement involves intravascular fluid (within, minuteri®.
hours), interstitial fluid (within a few days), and even intracellular fluid days to * few
weeks). The center of mass of the body moves upward about two centoe^ts. Lieg Wimm
decreases by about ntoepereeaat (1,5 liters); veins m4 tissues in the head and neck become
engorged; and it is speculated that central venous pressure increases. The universal symptom is a
feeling of fullness and congestion in the head. The effect on cardiac function is not clear; there
is no statistically significant decrease in heart rate ; cardiac output may be slightly increased. • .
A somewhat slower process is the loss of about ten percent of plasma volume aad wsd' cell
mass; these changes seem to be completed within two ta four weeks. An initial rise of about
2 gm/100 ml in hemoglobin occurs, then reverts toward normal, indicating that plasma loss iS
more rapid. No evidence of hemolysis exists, and there is no reticulocytosis in-flight.
4-9
U.S. Naval Flight Surgeon's Manual
Miuculoakeletal Effects
A transbiit'llecFease in appetite is almost a universal fincfing; this may represent si subcUmcal
symptom of motion sickness. After a few days, appetite and Caloric iutdke s^ekt to be strongly
correlated with exercise. Skylat data show an average weight loss of 5.1 %m the 28 -day flight,
3.8 kg on the 59-day flight, and only 1.1 kg on the 84-day flight. Daily exercise was deliberately
increased on the longer flights, and the experimental diets were relaxed to allow a higher intake
of calories and prc^ekw At ^is writing, it is unknown what would happen in the absence of
^ensise on lm§ flints; it may be a recfuired countenneasure. On short ffi^ts, a weight loss of
about fijine percent is expected and tolerable. Gastrointestinal function is esitntially normal;
there is a possibibty that abnormally high vascular pressure may be induced by straining at
stool.
Exemae c^padl^ is itnchanged in weightlessness provided that daily exercise is undertaken
to maintain gtnessund piievent significant muscular atrophy. Muscles not exercised (primarily
iMnk and leg muscles) do decrease in mass and strength.
There appears to be slow and so far inexorable loss of calcium from bone as a linear
function of time in weightlessness, at least up to 84 days. The average loss is about 140 mg/day,
or dbout !0.f to ® percent of total body calcium per month. This has been independent of diet
Wfd mms^^t M0%dajical pfobtems bave resulted; serum and urinary calcium, though increased,
have remained within normal limits. The cause Mid ultimate time course of this change remain a
research challenge.
Other Changes
The hormonal and electrolyte changes accompanying the above alterations are rich with
soblte eon&aciciicHis. Jhoi^hate is lost in proportion to calcium; sodium and potassium are lost
in approximate^portion to wei^t loss, and the latter may be a due to intracellular vobime
deereiee. In plasma, ACTH decreases markedly; coct^ol increases gradually; aldosterone
decreases; angiotensin doubles acutely then decreases to half normal concentrations. Urinary
aldosterone is persistently increased, urinary ADH persistently decreased. How all these changes
are related, and whether the total system response is a stable adaptation or represents narrowing
physiologic reserves, must be determined in^e future.
From the crew member's point of view, the environment is not chronically stressful,
althou^ it is certainly different. In addition to the vestibular symptoms and the constant
feeUng of congestion mentioned above, posture is changed, and more effort is required to sit or
stoop. Unused muscles are flaccid, and Sedentary occupations cause sleepiness. Getting to sleep
at ni^t may be troublesome, and tiie sleep period may be shortened by an hour or so. Skin
4-10
Space Fli^t Consideraiionfi
dryness and dandruff tend to be accentuated. Crew members are most comfortable when active,
and no decrements in intellection or coordination have occurred.
On reentry to normal gravity, the in-flight losses of body fluid and blood volume become
deficiencies, and the crew member exhibits mild to marked postural hypotension. Vestibular
reflexes are now inappropriate, and the crew member will experience vertigo, some difficulty in
wsdking, and possibly motion sickness. Unused muscles are weak and sore, and aerobic exercise
capacity is markedly decreased. Recovery is rapid, but ability to perform will be compromised
for a day or two, and demands on the crew should be scaled down accordingly.
It is against this picture of adaptive changes to weightlessness that candidates for space flight
must be measured. The picture seems to call for a conservative attitude towards cardiovascular,
renal, and endocrine disease in general. A lot of creative thinking and some risk-taking must be
exercised as standards are relaxed.
KMiography
Calvin, M., & Gazenko, O.G. (Eds.). Foundations of space biology and medicine (3 vols.) (NASA SP-374).
Washington, D.C.: U.S. Government Printing Office, 1975.
Johnston, R.S., & Dietlein, L.F. (Eds.). Biomedical results from Skylab (NASA SP-377). Washington, D.C.:
U.S. Government Printing Office, 1977.
Johnston, R.S., Dietlein, L.F., & Berry, C.A. (Eds.). Biomedical resulti of Apollo (NASA SP-368).
Washington, D.C.; U.S. Government Printing Office, 1975,
Outlook for space: Report to the NASA administrator by the outlook for space study group (NASA SP-386).
Washington, D.C.: U.S. Government Printing Office, January 1976.
Radiobiological factors in manned space flight (National Academy of Sciences Pablication 1487). Washing-
ton, D.C.: U.S. Government Printing Office, 1967.
War Department, Air Service, Division of Military Aeronautics. Air service medical manual, Washington, D.C.:
U.S. Government Printing Office, 1918.
4-11
o
o
c
c
GHAPTEfe 5 ,
INTERNAL MEDICINE
Section L Cardiology
Introduction
Basics of Electrocardiography
Complexes and Intervals
Vectorcardiography <
Cardiac Arrhythmias
Abnormalities of Conduction
Hypertension
Arteriosclerotic Heart Disease
Angina Pectoris
Acquired and Congenital Structural
Heart Disease
Principles of Cardiopulmonary Life Support
Peripheral Vascular Disease
Section 11: Gastroenterology
Esophageal Reflux/Hiatus Hernia
Peptic Ulcer Disease
Inflammatory Bowel Disease
Hepatic Disorders
Section ni: Hematology
Anemias — An Overview
Hemoglobinopathies
Section iV: Infectious Disease
Viral Disease
Tuberculous
Section rV: Infectious Disease /Comttsuedj
Malaria
Amebiasis '
Section V: Metabolic Disorders
Adrenal Disorders
Thyroid Disorders
Disorders of Glucose Metabolism
Hyperlipidemias
Obesily ' ''
Hyperuricemia
Section VI: Pulmonary Disease
Pulmonary Function Testing
Aviation Effects on Pulmonary Function
Asthma '
Spontaneous Pneumothorax '
Sarcoidosis
Pulmonary Embpli
Airway Burns
Section VII: Rerial Disease
Urinary Tract Infeetiofl- '•
Hematuria/Proteinuria
Nephrolithiasis
Section VIH: Malignancy
References
Bibliography
SECTION I: CARDIOLOGY
Introdiiction
The decfeoiardlofram {EC6) is m UnhiMe diagnciltffe aid and cliiiical tool. It is hBf tnearit
to repkce a iho'ku^ review of a patieril**^ me^dici^ Mstoty nor a carefully conducted physical
examination. Rather, the standitfd 12-lead EGG provides additional information to amplify the
basic cardiovascular examination. The EGG, if normal, offers no guarantee that a physician is
dealing with a completely normal cardiovascular system. Conversely, the abnormal EGG does
not necessarily imply immediate and unalterable catastrophe in a patient.
5-1
.U.S. Naval Tli^t Surgeon's Manual
In the majority of instances, a Flight Suigeon will be dealing with healthy, young adult
males. It is important, therefore, that the normal ECG be recognized in its various forms. The
following review stresses the identification and evaluation of the normal tracing. In so doing, it
is hoped that the identification of abnormal tracings can be aided.
Basics of Electrocardio^aphy
In order to determine whether a tracing is normal or abnormal, a clear knowledge of lead
placement (Figure 5-1), electrocardiogram components (Figure 5-2), and normal variants is
necessary. A definite and systematic approach should be adopted in the interpretation of any
electrocardiogram, quite simika- to the preflight checklist ueod in naval aviatioii.
The first step is to scan the ECG tracing for basic ileins of infomation and organpation.
Patient identification, including name, rank, and serial number^ iHould be on the tracing. Also
included must be relevant clinical information, such as age, sex, and current medication. The
tracing should present all 12 leads, with proper standardization in all leads and a 1.0 millivolt
(10 mm) deflection. This initial scan should also attempt to detect any 60 hertz interference
due to improper grounding, evidence of muscle tremor or similar artifacts, or a wandering base
line.
The ECG next ^ouM be exmnm^ for regularity of rhythm. If theSfe is aft i^^wtial
regularity, is it sinus, junctional, or idioventricular? With an irregular rhythm, & thfete a (lefinite
pattern to the irregularity? Are tiiere beats grouped in pairs? Are there dropped beats? b there an
erratic irregularity?
Finally, the initial scan should assess the rate of heart beat. This can be done if one
understands standard recording procedures. Hie electrocardiogram is inscribed on a background
of one millimeter with eirch fifth line thicker than the intervening four. The horizontal
^an between the thickened lines is 0.20 sec. (1/5 sec.). Thus, the time elapsing between
each mm square (at a standard speed of 25 mm/sec.) is 0.04 sec, the basic interval for
timing electrocardiographic events. Also, there are three-second mar^al markers on most
ECG pf^er; knowing this, the simplest system to estimate rate is by multiplying the
number of cycles in six seconds by ten. If the tracing is not long enough to allow this,
the number of fifths a second between cycles can be determined, and this number then
divided into 300.
Internal Medicine
4>
A = "Atrial" Uad
Srdi.C.S., R. S. B.
E = Lead at Right of Xyphoid
Process (Transitional Lead Betw^m
^ = Vi,4th , e_s^ R s;b.
@ =^2; 4**1 I.e. S., L.S. B.
: Between ^2 and ^4
0= V4. gth I c.S.,atM. C. L
© = V5. A_ A. L. at Level of ^4
% =■ V0 = M. A. L., at Level of V5
Figure 5-1. Precordial lead placement for horiisontal plane leadb.
5.3
U.S. Naval Ftj^t Surgeon's Manual
T
5
m
m
i
T
m
V
i
20 Sec, — »^
.„
i
H-
T
p
p
J
y
tiT—
N
4-
r
1
Figure 5-2. Basic electrocardiographic measurements and complexes.
Axis
The orientation of the heart's electrical activity in the frontal plane may be expressed in
terms of the "axis" or "heart position." To calculate the numerical axis, one must know the
[lexaxial Reference System, as presented in Figures 5-3 and 5-4. The electrical impulse writes
the largest deflection on the lead whose line of derivation is parallel to its path. It writes the
smallest deflection on the lead perpendicular to its path. To calculate the frontal plane axis, it is
easiest to look initially for the haA with the smallest deflection; i.e., the one most nearly
isoelectric. The axis of the heart is perpendicular, or nearly so, to this lead and lies parallel to
the lead with the largest deflection.
54
Internal Medicine
Figure 5-3. Development of hexaxial reference system
from standard bipolar and augmented limb leads.
U.S. Naval Fli^t Surgeon's Manual
(F)
Figure 54. Rexaxial refereiice system.
The normal axis of the heart is generally accepted as being between 0° and +90". There are
differences of opinion, ho>¥^ever, am png various authorities. The New York Heart Association
accepts +30° to +90°, whil^ Sodi-I^allai;es accepts +30° to +60° as nprmal. The meaning of
various axis deviations is shown in .T^le $4,, .
The principles and methods used in determining axis deviation also may be applied in
examining P- and T-waves. Here, it is best to plot the QRS and T-axis and to symbolize them as
long and short arrows, respectively. Note especially that the QRS-T angle should normally be no
greater than 60°.
Table 5-2 presents etiologies for both ri^t and left axis deviation.
.-1
5-6
Table 5-1
Axis Deviatibh Shii^
Classification
Extent
(Degrees)
Slight Ufl Axis Deviatidn '
Olo^ 30
(Probably WItiU
Slight Right Axis Daviation
80 to 120
(Prabably WNL)
Left Axis Deviation
0 to - 90
Right Axis Deviation
90 to 180
Marked Ueft Axis [^Istion
~ 30^- 90
Marked Right Axis Deviation
120 to 180
Extreme Left Axis Deviation
- 90 to -120
Extreme Right Axis Deviation
180 to -150
Table 5-2
Etiologieg for Axis Deviation
Right
Uft
Normal Variant
Normal Variant .
Mechanical Shifts -
Mechanical Shifts —
Inspiration, Emphysema
Expiration, Elevated Diaphragm
Right ventricular hypertrc^ihy
Irtm ^tas. Tumor, Pregnancy, etCv
Right bundle branch block*
Left ventricular hypertrophy*
Left posterior hemtblock
Left bundle branch block*
Dextrocardia
Left anterior bdnlbiock^
Left ventricular ectopy
Wolff-ParkirKon-White
Right ventricular ectdpy
Axis deviation mav or may not be prawnt in th«M imtsnces.
(Marriott, 10721.
Complexes and Intervals
Electrocardiogram complexes are groupings within an overall EGG trace which indicate
specific cardiac activity. Complexes which are displaced both above and below base line are
biphasic (or diphasic). Complexes E^dwing equal excursions above and below base lim aie
termed equiphasic. Leads in which equiphasic complexes, are seen are caOed isoelectrie.
5-7
U.S. Navaldi^t burgeon's Manual
P-Wave
The P-wave is an electrocardiographic representation of atrial depolarization. In a sinus
mechanism, the P-wave is the initial wave of the EGG complex. It is comprised of two segments,
the RA and LA depolarization waves, as seen in Figure 5^5.
LA
Figure 5-5. P-wave configuration diowing ri^t and left; atrial conttibutions.
The normal P-wave is less than 0.1 1 sec. in duration, is less than 2.5 mm in height, and can
show notching of up to 0.04 sec. The mean P-wave axis normally is 0"^ to +90° in the frontal
plane. P-waves normally are upright in I, II, and aVF iMfls*, inverted in aVR, and variable in HI,
aVL, jmd V leads. Normal variance includes the so-called coroniay sinus rhythm with inversion
of P-waves inll, HI, and atW (frontal plane axis of 45° to -75°) and normal P-wave
configuration in the V leads. Another normal variant is the left atrial rhythm, showing P-wave
inversion in n, in, aVF, and V2 or V3-V5.
Atrial depolarization is represented by the Tp or T^-wave' Oftd is oppoately directed to the
P-wave. Usually the Tji-wave is not discernible since it coincides with the QRS CQiaplex. It may,
however, depress the "J-junction" and can be confused with ischemic changes.
The genesis of P-wave activity and the vectorial relationship in the frontal and horizontal
planes are shown in Figure 5-6.
P-R Interval/Segment
The P-R interval is measured from the onset of the P-wave to the onset of the QRS complex.
It measures the time required for the electrical impulse to travel from the S-A node to the
ventricle. The normal range is from 0.12 to 0.20 sec, however, it is generally shorter in children
than in adults. The P R interval may exceed 0.20 sec. in some individuals, i.e., well^conditioned
young adults, patieilte with a high degree 'ftf vagal tone, thoas^iivho diow normalization by
standing, and those who show normalization during exercise.
5^
Intemel Medicine
R
Figure 5-6, Genesis of P-wave activity and vectorial relationship in &ontal and^ltoii^^n^ planesi
The P-R segment is defined as the interval after cessation of P-wave activity to the onset of
the QRS complex. Normally, it is isoelectric.
QRS Complex
This is the most important EGG complex, in that it represents ventricular activation
(depolarization). Here proper terminology is essential. If the initial deflectionis negative to the
base line, it is a Q-wave. The first positive deflection is an R-wave, whether or not it is preceded
by a Q-wave, A negative deflection following the R-wave is an S-wavft. Subsequent positive
deflections are termed R', R", etc., with subsequent negative deflections teitoed S' and S". .
5-9
U.S. Naval FISgbt Surgeon's Mamial
If a QRS complex is exclusively positive, points at the beginning and end of the complex are
labeled Q and S, respectively. An entirely n^ative wave is called a QS wave.
In an inspection of a QRS complex, there are six features of importance which should be
examined:
1. Duration
2* Amplitude
3. Presence (and duration) of Q-waves
4. Electrical Axis
5. Precordial Transition Zone
6. Timing of "Intrinsicoid Deflections" in and Y^.
Duration. The normal duration of the QRS complex is 0.05 to 0.10 sec. Occasionally,
duration intervals exceeding these criteria, in either direction, are encountered and may be
normal. These durations are based on measurement by standard leads. Use of precordial leads
may result in shghtly longer durations.
Amplitude. The minimal frontal plane QRS amplitude is 5 mm. Minima] amplitudes using
precordial leads are V^, Vg-S mm, V2, V5-7 mm, and V3, V4-9 mm. Normal upper limits are
more difficult to estabhsh, although frontal plane QRS ampUtudes of up to 20 to 30 mm are
seen in lead II in some normal individuals. Maximum amplitudes with precordial leads may be
25 to 30 mm, and on occasion even to 35 mm.
Q'Waves. This feature of the complex is important, but often it is difficult to assess. Salient
features to observe with Q-waves are the width of the Q, leads in which the Q's appear, and the
clinical settings, Sfcse is important, with a diminutive Q of 1 mm having possible significance that
a QS of 10 iriin does not have. A narrow Q in I, aVL, aVF, and Vs-Vg is normal, and the
absence of such a Q-wavB ttiay be of si§3ific£0ice„ QS or Qt complexes are normal in aVR, while
a QS may normally be found in HI, Vx , or V2. Duration of the Q-wavC is considered normal up
to 0.03 sec.
Electrical Axis. The electrical axis of the QRS complex is of consequence and, as noted
eai^lierf«hould form an angle with the T-wave no greater than 60°.
Precordial Transition Zone. This refers to the horizontal plane rotation. The direction of
rotation is specified as viewed from the inferior cardiac surface looking upward from the
diaphragm. The normal transition zone is V3-V4. A clockwise rotation is a shift of the
5-10
horizontal plane axis to the left or a delay in the typical LV pattern beyond V5.
Counterclockwise rotation shows dii^laceftient to the right, resultnig in a typical LV pattern as
early as V2 .
Intrinsicoid Deflection. Since direct epicardial lead placement is impractical, indirect
precordial leads must be used to produce patterns of precordial activity. In these clinical leads,
the downward deflection is the analogue of the intrinsic deflection, i.e., the so-called
intrinsicoid deflection. The intrinsicoid deflection records the instant at which the cardiac
muscle immediately below a unipolar electrode has been completely depolarized. Figure 5'7
depicts the sequence of ventricular activation and the resultant complexes obtained from RV
and LV unipolar electrodes. Figure 5-8 shows the vectorial relationships, in the frontal and
horizontal planes, of the ventricular activation. The intrinsicoid deflection, i.e., the peak of the
R, should be reached in Vj within 0-02 sec. (0.03 sec. maxnnally) arid in V5, V5 within
0.04 sec.
ST Segment
The ST segment is that part of the tracing immediately following the QRS with the
"take-off" point called the "J-junction." The ST segment should be observed for its level
relative to the base line and for its shape. Normally, the ST segment may be initially elevated
1 mm in the standard leads and 2 mm in precordial leads, although in some instances of early
depolarization up to 4 mm may be observed. The ST segment should not be depressed beyond
0.5 mm.
The contour of the ST segment is a gentle, upward slope which blends into the proximal
limb of the T-wave.
T-Wave
This wave represents the recovery period of the ventricle or ventricular repolarization. The
T-wave normally is upright in I and II and in V leads over the LV. It is inverted in aVR and is
variable in other leads. Also, the T-wave normally is upright in aVL and aVF if the QRS is
greater than 5 am. The QRS-T angle, as noted earUer, should not exceed 60" in the frontal
plane.
In precordial leads, the tendency to inversion of the T in early leads diminishes rapidly with
age. In same normal athletic young adults, the T-wave inversion occasionally extends beyond
V4. Generally, the shape is rounded with some loss of symmetry. T-waves usually are not larger
than 5 mm in standard leads or 10 mm in precordial leads.
5-11
U.S. Naval Flight Surgeon's Manual
Figure 5-7. Sequence of ventricular activation.
5-12
Internal Medicine
Figure 5-7 (Continued). Sequ^iliSe of ventricular activation.
QT Duration
This feature of a tracing measures the total electromechanical duration of ventricular
systole. It varies with heart rate, sex, and age. Generally, the QT interval is less than one-half the
preceding R-R interval. At heart rates belov\r 65 bpm, the QT falls further below this value. At
bpra above 90 to 100, it often exceeds one-half the R-R interval.
UWave
This wave represents a ventricular after-potential. Normally, it is smaller than the preceding
T-wave. Its normal polarity is in the spne direction as the T-wave. The U-wave is best discerned
in V3.
5-13
U.S. Naval flight Surgeon's Manual
P
C
FRONTAL
PLANE
Figure 5-8. Sequence of ventricular activation showing vectorial rdationBhip
in frontal and horizontal planes.
5-14
bttemtil Medicine
Vectorcardiography
The vectorcardiograph (VCG) records changes in the spatial orientation, directioii, and
magnitude of electrical activity of the heart. In so doing, it demonstrates the sequence,
direction, magnitude, and distribution of the forces generated within the heart.
Vectorcardiography increasingly is being utilized as a diagnostic tool. It has become a
routine procedure at the Naval Aerospace Medical Institute, but may not yet be available in
some cardiology clinics.
The vectorcardiograph is not a replacement for flie standard wsaler eleetrocardiograph:,
although the two generally correlate well. The scaler EGG is the standard currently used in the
study of arrhythmias, although advances in vectorcardiography are beginning to make it useful
in this field. Both the EGG and VCG can be used to demonstrate myocardial hypertrophy,
atthcnigh the YGG may be superior in the idenlificaiSon oF early hypertrophic changes.
Vectorcardiography readily demonstrates the subclasses of right ventricular hypertrophy, and it
is capable of providing diagnostic information concerning identification of the hemiblocks.
Abnormal or altered forces due to myocardial damage are displayed by both the EGG and VGG.
Hie VCG, however, is helpful in (l)the diagnosis of true posterior nifketion and (2) the
eonfiritiation of the presence of an infarction suspected by findings on the scaler ttayng.
Vectorcardiography is Based on flie dipole theory in VfW^ the electried aeli^ty generated
by the heart is treated as a eitl^e dipole moving within a volume conductor. A dipole is defined
as a source providing a single pair of opposite electrical charges, as shown in Fi^re 5-9. The
VCG records the electrical field created by activity of the dipole.
/
/
/ / ' \+
I { K
\
\
\
_\ \
FigitfeS"-?. Di|Hde.
U.S. Naval Fli^t Surgeon 'b Manual
Dipole theory, as used in vectorcardiography, assumes:
1. The genteP of, <^mmdrsi0ity of iii^Jkeart is the anatomie cfeater of flie rfiest.
2. TheposithFeehiu^eigthek^ *
3. I, n, and IH are equidistant from the center of electrical activity.
4. "Hie torso can be assumed to be spherical.
5. All tissues and fluids are ecpially good conductors of electrical potential.
It must be noted, however, that because of oerfaili inaccuracies in assumptions 2 through
5 above, mathematical confections have been made in an attempt to compensate for fhe errors
in these assumptions, resulting in "corrected" orthogonal lead systems in VCG. figure 5-10
shows the changes in recording obtained as the electrical force field (dipole) moves through the
heart muscle. At time 1, as the positive charge nears the recording electrode, a progressively
positive wave is recorded which rapidly moves to peak potential. At that time, the positive
charge is direetly under the electrode. As the dipole continues, the charge beneath the electrode
changes in a negative direction, resulting in an increasing negative deflection {time 2). As the
dipole progresses, there initially is a complete negative deflection followed by a gradual return
of the negative recording to the neutral position (time 3). The down stroke from maximum
positive deflection to maximum negative deflection is termed the intrinsic deflection.
The sequence of ventricular activation, as represented by instantaneous vectors, is shown in
Figure 5-11. The manner in which these instantaneous vectors can then be used for construction
of a vector loop is shown in Figure 5-12. Here the vectors are repositioned to show a single
point of origin, with the order of sequence remaining intact. The vector loop then can be
constructed by connecting the tips of the instantaneous vectors.
A three-dimensional loop is termed a spatial loop, with its projection in a single plane called
a planar loop. The three planar projections, Or loops, generally used in vectorcardiography are
the frontal, horizontal, and sagittal. These projections are obtained throu^ use of orthogonal
bipolar leads. The frontal plane projection is obtained by simultaneous x and y recording, the
horizontal plane projection by x and z leads, and the sagittal projection by y and z recordings.
The coordinate system used in construction of VCG projections is shown in Figure 5-13.
EGG Anomalous' Findings '
During the period from November 1974 to November 1975, some 24,000 cardiographic
tracings were received and reviewed at the Naval Aerospace Medical Institute. Approximately
five percent of the ECG recordings showed the SiS2S3 pattern, an interesting variant of normal.
In this pattern, deep S-waves are present in leads I, II, and III, while AVR displays a large
terminal R-wave, the reciprocal of an S-wave in that lead. Frequently, the pattern observed
S-16
Intenial Medidhe
shows virtually identical complexes in all frontal plane leads, except for differing magnitudes of
electrical potential in different leads. Often, this leads to confusion in calculating the axis of the
heart. Occasionally, and not infrequently, the axis appears to be deviated, with the QRS
duration prolonged (0.10-0.11 sec.).
Time 1
Electrode
Time 2
Time 3
Dipole
Movement
,^0^ — ^ — es- ©s
Recording
r
Figure 5-lQ. Changes in recortling obtained as the electrical foice field (dipple)
moves through the heart muscle.
5-17
U.S. NavaLFIij^t Surgeon's Manila]
■
E
\J
. . — j_
E
a\ 4
B
B
Figure 5-12. Construction of vector loop using instantaneous
vector repositioned to sin^e point of view.
R
S
L R
P 5
L A
P
F.P.
(X)
1 \z\
<X) tZ)
A H. P.
1 S.P.
Figure 5-13. Coordinate system used in construction of VGG projections.
In reality, vectorcardiographic analysis reveals a terminal, right-sided, superoposterior
conduction delay, in which the forces beyond 60^70 msec, are pfled atop one another. The area
inscribed by these forces is generally small; certaiidy, the area of the terminal forces as depicted
by VCG is sjnaller than that observed in the standard ECG tracing. In fact, it is the terminal
forces which give rise to the apparent axis deviation on routine ECG. On vector loop analysis,
maximal QRS forces are normal (O'* to 90°) in virtually all instances.
The S^SgSg pattern most likely depicts an accentuation of normal, ri^t ventricular, basal
outflow tract forces — representing .an jurea rather deficient of Purkinje fibers and the final
regions of ventricular depolarization.
Intern^ Medicine
In the horizontal plane vector loop, terminal forces may be sufficiently displaced posteriorly
and rightward to give rise to an RSR^ pattern in on standard tracing. This may suggest
incomplete right bundle branch block (RBBB), although VCG clearly demonstrates that the
terminal forces do not enter the right anterior quadrant, distinguishing this pattern, thereby,
from that of RBBB. Figure 5-14 compares the vector loops, in the horizontal plane, of the
normal, the S1S2S3, and RBBB patterns.
Cardiac Arrhythmias
Extrasystole
Extrasystoles can arise firom virtually anywhere in the heart. They are a common finding in
the normal heart as well as a manifestation of disease. In aviation personnel, extrasystoles are
most often discovered in routine electrocardiograms, but patients may present with
symptomatic extra or skipped beats or other cardiovascular complaints. The job of the Fli^t
Surgeon is twofold. First^ he must determine if the extrasystoles are a normal variant, or, rather,
the first sign of subtle, valvular, congenital, ischemic, or metabolic disorders. Secondly,
regardless of the presence or absence of pathology, the risk of subsequent tachyarrhythmias
must be evaluated.
In determining if organic heart disease is present, a complete history and physical
examination are essential. Laboratory studies should include resting and exercise ECG's, cardiac
series, and echocardiograms. Cardiac catheterization may be necessary on occasion. The ECG
characteristics of the extrasystole (Table 5-3) are often not helpful in deciding if pathology is
present since both ventricular and supraventricular extrasystoles appear in the normal
population. However, multiform or frequent ventricular beats, particularly if they appear close
to a T-wave or upon exercise, are su^eStive of organic heart disease.
If organic heart disease is discovered in the evaluation of extrasystoles, generally the aviator
is permanently grounded. However, even if the extrasystoles are a "aormai variant,'' the Flight
Surgeon should be alert to tiie possibility of subsequent tachyarrhythmias. This risk cm never
l^e completely elimkiated, but with no prior history of tachycardia, unexplained syncope, or
other cardiopulmonary symptoms, the aviator may continue to fly. ECG monitoring over
24 hours may be useful in questionable cases.
Tachyiuthythiiuas
Tadiycardia in the aviation community presents in one of three ways: (1) the healthy
individual with a history of tachycardic episodes, (2) the healthy patient who presents with an
acute supraventricular tachyarrhythmia, and (3) a potentiaUy Ufe-threatening tachyarrhythmia
arising in the setting of an acute cardiopulmonary emergency.
5-19
U.S. Naval Flight Surgeon's Manual
A) Normal H.P.
Vector Loop
(Z)
B) S^SjSg H.P. Vector Loop
/
/
/
/
^ L
(X)
C) H.P. Vector Loop in
Right Bundle Branch
Block
/
/
\
/
/
■^L
(X)
A
(Z)
Figure 5-14. Comparison of horizontal plane vector loops
for nornid, S1S2S3, and right bTindle branch block patterns.
5-20
Intemal Medicine
Table 5-3
EGG Characteristics of Extrasystoles
Supta ventricular
V ef ILI tUUIQI
P-wave may be present.
Usually no P-wave h present.
QRS' complex is similar to normal
QRS. It may be aberrantly conducted.
But even then, initial forces are
often similar to normal QRS, and
the entire complex is less than
0.16 sec. in duration.
QRS' complex is bizarre with long
duration and little resemblance
to normal QRS.
Minimal ST and T-wave abnormalities
are present.
Abnormal ST segment and T-wave are
common.
Sinus node will "reset" producing no
pause following the extrasy stole.
Sinus node will not "reset;" the normal
impulse will be blocked, artd a
"compensatory pause" will occur follow-
ing the extrasystole.
The patient with a prior history of tachycardia is generally disqudified from aviation since
the risk of future tachyarrhythmias is significant. Such tachycardias, if they were to occur in a
crucial aviation setting, could be seriously disabling. Patients with a history of unexplained
syncope, sudden lightheadedness, or shortness of breath are suspect for having paroxysmal
tachycardias. The Flight Surgeon must be convinced that tachycardias are not present before
allowing the patient to fly. A 24-hour EGG monitor can be very useful in this regard.
«
The first episode of a tachyarrhythmia may present to the Flight Surgeon as the idiopalMc,
acute onset of palpitations with varying degrees of symptomatology. A supraventricular
mechanism is virtually always the source, and effective therapy depends upon differentiation
among the four major types (Table 5-4).
Supraventricular Tachyarrhythmias
Sinus Tachycardia. This is iic^ver a primary cardiac rhythm disturbance. Treatment must be
aimed at the appropriate cause (fever, thyroid dysfunction, hypovolemia, etc.). An aviator's
future depends on the identifScato of this underlying cause.
Atrial Fibrillation. In the mildly symptomatic, otherwise healthy patient, this rhythm may
respond to sedation and bed rest. If therapy is indicated, Digoxin (0.50 mg I.V. followed every
four hours by 0.25 mg I.V. to a maximum of 1.00 to 1.25 mg total dosage) will slow or break
5-21
U.S. Naval Flight Surgeon's Manual
the arrhythmia. If severely decompensated, 200-watt-sec cardioversion (i.e., synchronized with
QRS countershock) should convert, but this must be used cautiously if more than one milligram
of Digoxin has been given. Propranolol (1 mg slowly I.V. every 5 min. x 5, if neceflsary, or 20 to
40 mg orally) may be useful. Once the fibrillation rhythm is broken and a sijm* mechanism
returns, chronic medications may not be needed. Nevertheless, the patient's aviation career isi
over, and a cardiac workup for organic disease is indicated. Digitalis and propranolol . are
effective prophylaxis for this arrhythmia, if required.
Table 54
Differentiation of Atrial Arrhythmias
Onset
Rate
Morphology
Vagal
Response
Sinus Tachycardia
Slow
Up to 195
Normal P & QRS
Gradual slowing
Atrial Fibrillation
Sudden
Chaotic
atrial pattern.
Ventricular
response
irregularly
irregular
QRS normal or
aberrant and
may vary.
Chaotic atria
Slows ventri-
cular response
Paroxysmal
AtPial
Taehycardia
Sudden
Atrial mte
140.210
with
ventricular
rate depending
on status of
AV node
QRS normal or
aberrant. P is
either < 0.1 2
sec. from
QRS or
retrograde
Sudden
termination or
no response
Atrial FluttBr
Sudden
Atrial rate
250-350 with
ventricular
rate a set
increment
(2:1; 3:1;
4:1; etc.)
QRS normal or
abnormal.
Classic flutter
waves in
atria
Changes
ventricular
response
(slower]
Paroxysmal Atrial Tachycardia. This arrhythmia will frequently convert merely with vagal
maneuvers (including I.V. Tensilon given as a 1 mg test dose followed by a 10 mg bolus,
slowly injected). If this does not convert the patient and symptoms are mild, sedation may
be all that is xequired. Pi^xin, propianolol, and cardioversion can be used as in atonal
fibrillation. As with all the tachycardias, a cardiac workup is indicated following conwrsiDto,
but regardless of the presence or absence of organic disease, the patient is disqttalified from
5-22
Internal Medicine
aviation. Digoxin and propranolol are effective prophylaxis after return to normal sinus
rhythm but frequently are not needed.
Atriai Flutter. This rhythm fe virtuaUy always responsive to low wattage cardioversion
(25 watt-sec to 100 watt-sec). It usually reflects organic heart disease and disqualifies the
patient from flying. Prop^laxis,. if needed, can be accomplished by Digoxin and/or
propranolol. '
Ventricular Tachyarrhythmias
The most serious way a tachyarrhythmia can present itself to the flight Surgeon is the
life-threatening ventricular tachycardia and fibrillation that accompany acute emergencies
(trmima, infarct, pMlnuJtuif «in>K»luS, etc.). In addition to life support measures (see section on
cardiopulmonary life support), venttictilar fibrillation, and tachycardia must be immediately
(Jil^osejJ pxfl treated.
Ventricular Fibrillation. This is Ht^pUy a chao^mttf fikatiig ventricle with no cardiac
oilt^ilft,. 'Immediate, 400 wattnSee ddaaallation is needed, Wiowed by lidocaine (1 mg/kg I.V.
bolus, then a 4 mg/min. I.V. drip). Basic life support techniques must be effective for these
maneuvers to work. Propranolol (1 mgl.V. q.5 min. x 5 slowly) may help in resistant cases
along with repeated defibrillation attempts.
' TmtriMeO' tachymdia- This rhythm may resAilffite a^praventrieuiar tac%card!a with
flliri^^rd •|iteran^;' M iiS'loWer rate (120 to 150 bpm) and the absence of an effective cardiac
output should readily identify it. A sustained tachycardia should be immediately cardioverted
with 400 watt-sec defibrillation followed by hdocaine as above. Short bursts of ventricular
tachycardia interspersed with sinus rhythm can be treated by lidocaine alone.
In all of these tachyarrhythmias, the Flight Surgeon must be prepared to treat acutely.
Periodical review of all of these drugs and re£aroil»aps|ltiOTi with the defibrillator and its
^chronizing mechanisms for cardioversion should be a routine procedure.
Bradycardias and Cardiac Standstill
Extremely slow ventricular rates result from severe conduction system dysfunction (marked
sinus suppression and high degrees of A-V block). Cardiac standstill (asystole) is bradycardia in
its most extreme form. These probing atei»st , alwJ^a feom A ©ardi#IHitoonafr
raitastrophe, but, on occasion, they can be rtie result of a httfe vagal effect (iatrogenic or
ofterwise). A blow to the chest and atropine (0.5 mg I.V. q.5 min. x 4 as necessary) may be
helpful, particularly in high vagal state's. Epinephrine (0.5 mg I.V.) and isoproterenol drips
5-23
U.S. Naval Flight Surgeon's Manual
(titrated to response) are the next drugs to be used. A transvenous pacemaker may be required
in severe cases. Life support measures should always he c«ded out while these therapeutic
maneuvers are attempted.
Miscellaneous ,
Asymptomatic sinus bradycardia (often with junctional escape beats) is a benign and very
common rhythm in healthy young men. It is not disqualifying. Similarly, wandering atrial
pacemaker and the various nonsinus atrial pacers (left atrial, coronary sinus rhythm) are not
disquaUfying.
Abnormalities of C!onduction
The heart not only is capable of initiating its own rhythtltiiC d^oltt^itiott Imt ^o Rae
speciahzed neuromuscular tissue capable of conducting the depolarization wave throughout the
cardiac muscle. From the S-A node (Figure 5-15), the depolarization wave spreads throughout
the atria via three main internodal tracts. These are the anterior (Bachman), the middle
(Wenckebach), and the posterior (Thore). BetWeeA' th«de tracts, interconnecting fibers merge
just proximal to the A-V node. Not iiU fibers enter the A-V node, however. Sbmi« fibers bypiss
it and enter ii3ib conductioti sytmm- distal to ^is node.
The A-V node is located on the endocardial surface of the right side of the atrial septum.
Here, the impulse is normally delayed for approximately 0.07 sec. The impulse then passes into
the His bundle, located on the endocardial surface of the right side of the irtrial sq)tum distal to
the A-V node. The common (His) bundle subdivides in the membranous portion of the
ventricular septum into a right bundle branch and a left bundle branch. The left bundle branch
further subdivides into the anterosuperior division and the posteroinferior division. After
traversing the rig^t and left bundl@s, the impulse passes into multiple small branches (the
Purkinje system) and into the ventricular myocardium.
The principal classes of condttctitm dinormality are presented in Table 5-5. The following
sections describe these classes in some detail.
1** A-V Block
This block occurs when atrial impulses are conducted to the ventricles but are delayed. The
P-R interval is prolonged for a period greater than 0.20 sec. This block may be observed in a
variety of cUnical situations such as rheumatic fever, acute infectious disease (e.g., diphtheria),
drug th^Spy (e.g., digitahs, quinidine, propranolol), coronary artery disease (e.g., inferior
myoc«#al infarotion)^ and^ a normal variant in athletic young adults, with mediation thfoi^
vagdt Ittfluence at Die A-V node. i.
5-24
Internal Medicine
Figure 5-15. C3s#^C Conduction systetti.
Table 5-5
Principal Conduction Abnormalities
Incomplete A-V block
1° A-V block
2° A-V block
Mobltz I
Mofeit?ll,-
High deflree- A-V block
Complete A-V block
Right bundle branch block
Left bundle branch block
Left anterior hemlbtock
Left posterior tpmlWock
Complete l^ft bundte .branch block
Bilateral bundle branch block
Pre-excitati on (Wolf f -Park! nson-Wh 1 te)
5-25
U.S. Naval Fli^t Surgeon's Manual
Patients should be evaluated for normalization of the P R interval while standing and
following exercise. If the F-R interval shortens with an increasing heart rate, i.e., the normal
physiologic response, there is no contraindication to duty invohing flying.
2** A-V Block
This block, also known as Mobitz I or the Wenckebach phenomenon, is generally considered
to be benign and may be observed in normal patients with a high degree of vagal tones
(Figure 5-16). However, organic heart disease can give rise to this phenomenon and should be
considered in the evaluation. The defect is considered to be at the nodal level. If found in
association with infarction, it is geneKilly rever^le aftd does not require pacemaking.
Figure 5-16. 2" A-V block (Wenckebach).
The diaposis for this condition is made using the fotttiidng criteria:
1 . Single ventricular beats are dropped in a cyclic fashion.
2. The first atrial impulse of the cycle is normal but.may show a 1** A-V block.
3. Each subsequent P R interval beeomes pro^^vely longer, until an atrial impulse fads
to generate a ventricular response, i.e., a dropped beat.
Aviation personnel showing the WenckefeaiCh phenomenon are generaUy considered to be
physicany qaaHfied for flying if no underl^ oiganic heart disease is found and if stress
testing and physiologic maneuvers fafl to ihthice forther block or significant rhythmic
disturbances.
5-26
Internal Medicine
The Mobitz II phenomenon is a periodic failure of the ventricle to respond to an atrial
impulse which one would expect to be conducted. In this condition, which may be associated
with a 1° A-V Bock, tlie P^P amd the P-R itttaMr«Is «eMialii cttitetant (Figute:0»l'7). the site of
jntoteieieati is infranodal. The cendition is considered more serious than Mobitz I and may
progress to a complete A-V block. Pacemaker implantation should be considered, and the
condition obviously renders jt |^itient|V0t|>h5J||cally ^a||fied (NPQ) for aviation.
NASHUA CORif-OR AT10». C -631 50
84
88
88
82
A
.\ IS \ 16 V \^ le
\ A-V
84 174 ^ V
Figure 5-17. Mobitz H, 2° A-V block.
High Degree A-V Block
In this condition (Figure 5-18), there is a fAife of more iJisan oJtti-haif d£ the atrial
complexes to produce a venMeular response. The P-F latetTail k een^ant; W is the P-R intoPVil
t&t those complexes being conducted. Again, pacemaker implantation may be necessary, and
the condition is NPQ for aviation.
Complete A-V Block (3** A-V Block)
In this condition (Figure 5-19), the atria and ventricles beat independently of one another.
The ventricular rate depends upon the site of the escape rhythm (junctional or ventricular). This
condition again is NPQ for aviation.
5-27
U.S. Naval Flight Surgeon's Manual
Figure 5-18. High degree A-V block.
. I ^
Figure 5-19. 3° A-V Hock.
o
5-28
lotelKKaljIilBflicine
Minor A-V Blocks
There are two conditions of conduction block which a Flight Surgeon should understand
but whidi are relatively insignificant and are presented for interest only. The first of these is
intra-atrial block which represents atrial enlargement rather than a true block. In this condition,
the P-wave duration is less than 0.12 sec. and shows deep notcliing. The peak interval of the
notched P-wave is greater than 0.04 sec.
A second minor condition is the S-A block. An incomplete S-A block is an infrequent failure
of an impulse from the S-A node, resulting in a dropped beat. This may be represented by the
occasional absence of a P-QRS-T sequence.
A complete S-A block occurs when no impulses arise from the S-A node, resulting in atrial
standstill atul the absence of P-waves. Two things can bappeii in this case. There is temporary
cardiac standstill, or an escape pacemaker, either junctional or ventricular, assumes the role of
pacemaking. A complete S-A block, a rare condition, can be brought about by drugs (digitahfi,
quinidine), coronary artery diiease, inflammatory or infectious diseases, or physiological
disturbances (carotid sinus sensitivity and increased vagal tone).
Bundle Branch Blocks
Bundle branch blocks involve a delay or interruption in conduction Hu-ou^ either the right
or left bundle, ultimately giving rise to excitation of th& Ventricles in "series" rather than
"paraUel." This delay prolongs the QRS time to Q>|2 mi^> m longer.
Right Bundle Branch Block (RBBB). This conduction problem may be found with a variety
of organic heart disorders such as diseases producing RVH, coronary artery disease, eonpital
lesions involving the septum, and inflammatory or infiltrative myocardial diseases. It may,
however, also be found in individuals without evidence of heart disease.
The sequence of ventricular activation in RBBB is shown in Figure 5-20, with the resulting
recordings presented in Figure 5-21. Initial septal activS^on is normal; thus, an initial smaU
R-wave will be recorded in Vi, as will a small Q-wave in Vg. Since the right bundle branch is
blocked, the impulse will travel down the left bundle branch into the LV, resulting m an S-wave
in Vi ami an R-wave in ¥5. RV depolarization follows, as the LV activation wave envelops the
RV free wave, resulting in an R' in Vi and ^i S^a^ ii^J^fi- The QRS duration is 0.11 to
0.12 sec. or greater.
If physiologic maneuvers and stress testing faU to uiduce any increase or change in the
degree or type of block, aviation personnel are physically qualified with this condition. A or
exception is right bundle branch block acquired in association with coronary artery disease.
5-29
DJS. Nlivtf Fli^t Surgeon's Manual
5-30
Intecnal Medicino^
n
FBMHFBf HQ WHmTB I
Figure 5-21. RcBulting recordings from Figure 5-20.
Left Bundle Branch Block (LBBB). This condition may occur in conjunction with a variety
of organic heart disorders, the same as for right bundle branch block. One difference, however,
that left bundle branch block rarely is found in normal individuals Wthotit evidence of
disease. ,
IS
The seouence of ventricular activation in left bundle branch block is sbown in Figure o-22,
Tdth^e corresponding recording presented in Figure 5-23. Septal activation begins from right
to left, giving rise to a small Q-wave in Vi and an initial small R wave in Vg. Smce the left
bundle branch is blocked, RV activation proceeds normally, giving rise lo an R-wave m Vi and
an S-wave in ¥5. Delayed LV activation begins as the impulse passes into the LV, giving rise to
an S-wave in and an R-wave in The QRS duration is 0.12 sec. or longer.
A poUcy has been estabUshed at the Naval Aerospace Medical Institute to require complete
evaluation, including cardiac catheterization, if evidence of acquired LBBB is found. If this
evaluation is negative, aviators may be returned to duty involving flying.
Hemiblockfi
The left bundle branch divides into two m&n divisions - the left anterior division
(anterosuperior division) which activates the anterior papillary muscle of the left ventricle and
the left posterior division (posteroinferior division) which activates the post papillary muscle of
the left ventricle. If one division is interrupted, LV activation be|ms exclusively tiiroughthe
other division, thereby shifting the resultant vectorial forces. Figurr5-24 illustrates this A^m
a hemiblock pattern using limb leads. Here, the anterior papillary muscle is supenor andiMeral
to the postmor papiUary muscte. If the anterior division is blocked, initial forces are downward
5-31
U.S. Naval M^t Suigedoiife Manual
P
A
(I
nee of ventricular activation in left bundle branch Mock.
5-32
bitetaid Medicine
and to the right, inscribing a Q inl a «maU R inlH. Subse<iuen forces are d.ected
superiorly and to the left, Writing an E in I a«<* an S in HI, giving rxse to left axxs deviation. In
left posterior hemiblocks, initial f Otces spread upwards and to the left mscnhing an R m I and a
Q in m while subsequent forces are downwards and to the right, producing RAD.
Figure 5-23. Resulting recordings from Figure 5-22.
5-33
U.S. Naval M^SB^san-l Mmnal
■m hemiWoiefcs, the QRS interval is ndt drajnaticaBy increased, changing 0.01 to 0.02
iHost. A moife iiiafled'JfeAig of fte criteria for hemihlocfe is presented in Table 5-6.
Table 5-6
Criteria for Heiuiblocks
Left Anterior
Left Posterior
Hemiblock
— ttfiflftl^
Left axis deviation
Right axk deviation
(-60°or»
Small Q in l.sn^alf
Small R in 1, small
R in III
Q in III
Max QRS duration:
QRS duration;
0.09 -0.10 m
0.09-0.10 sec.
No evidence of RVH
(adapted from Marriott, 1972>,
Unless there is evidence of underlying organic heart disease, e.g., coronary artery disease or
valvular heart disease, or there is a change in the type or increase in the block disclosed by
physiologic maneuvers or stress testing, aviation personnel generaUy are considered physicaDy
qualified.
Wolff-Parkinson-White
The Wolff-Parkinson-White phenomenon (W-P-W) has in the past been referred to as
"pseudo-BBB." The common denominator between W-P-W and BBB is a widened QRS;
otherwise, there are Um hilarities. With BBB, as shown in Figure 5-25, the ventricles are
activated in "series," and the delayed ventricular impulse |8 %dded on" to tiie end of the
normal QRS wave. With W-P-W, as shown in Figure 5-26. -Otte ventricle part thereof, is
activated eariy, and the resultant deflection or pre-excitation wave is "lidded on" to the
beginning of the QRS complex.
Q S
Figure 5-25. Comparison between normal QRS complex
and that in bundle branch block.
5-34
Internal Medicine
tQRS,-^P>•R
Q S
Figure 5-26. Comparison between normal QRS complex
aijcljlhat in Wol££-Paridini^»-^" '■
The W-P-W phenomenon is caused by an accelerated conduction to one ventricle through an
accessory pathway (Kent, Mahaim, or James tracts) which bypasses the A-V node. The classic
pattern of the recording as this occurs consists of a shortened P R interval, a prolonged QRS
complex, and slurred initial QRS forces, the so-calted-ddta wave (Figure 5-27). Atypical
patterns have been observed^ witJi normal P^R intdrvals and nornial QRS times, yet a delta wave
h dMinctly present on EGG and VGG.
mSJCAL ELECIHOf«;S DIVISION
F«4MFhPER' HO. B2rO-a7B
Figure 5-27. ECG wave patterns in Wolff -Parkinson-White.
The Wolff -Parkinson-White phenomenon may be subdivided. littto group A, m& ^&Mvt
ventricular complexes in Vi» and group B, with predominanHy negative eompkxes tin ¥i. The
abnormaUty in either case is relatiViel|?vbenign. It is frequently seen in males without heart
disease, but it may be seen in idiopathic hypertrophic subaortic stenosis (IHSS), coronary artery
disease'(CAD), and Ebstein's disease. If arrhythmias are noted, they are as foUows:
1. Paroxysmal Atrial Tachycardia (PAT) in 70 percent
2. Atrial Fibrillation (AF) in 16 percent
3. Atrial flutter in 4 percent
5-35
U.S. Naval Flight Surgeon's Manual
4. Unidentified Supraventricular Tachyarrhythmia (SVT) in ] 0 percent.
Aviation personnel with W P-W are considered physically qualified if there is no history of
arrhythmias nor documented tachyarrhythmias during physiologic maneuvers, stress testuig, and
Holter monitoring.
Hyperten^on
Blood pressure control is determined by factors that regulate the circulation volume
(aldosterone, other stcroi(Js, renal blood flow, central osmoreceptors), the peripheral resistance
(catecholammes, angiotensir. 11, arteriolar reflexes), and cardiac contractihty (catecholamines,
other less understood factors). Key inputs to the system come from the carorid sinus, the
afterload on the ventricle, and the kidney's juxtaglomerular apparatus. Considerable research is
auned at these interactions i« attempts to understand derangements of blood pressure control
Nevertheless, only about one , to five percent of aU cases of hypertension are ever found to have
a clear etiology (e.g., adrenal malfunction, renal artery stenosis, pheochromoeytoma,
coarcts. etc.). The vast majority fail into the wastebasket category of "essential" hypertension.
Regajdless of its cause, however, an elevated blood pressure is a significant risk factor for
coronary artery disease, left ventricular hypertrophy and failure, cerebrovascdar disease, and
renal dysfuncfc. The approach to the aviator with hypertension should be stepwise. First, the
diagnosis should be made with the patient resting m a nonstressful situation. Orice the diagnosis
of hypertension (resting blood pressure h%her than 138/88 mm Hg for aviators) is made, a
careful assessn.ent should be made of any existing hyperleusive "damage" (e.g., exercise
mtolerance, left ventricular hypertrophy, renal dysfunction). The presence of hvpertcnsive
"aggravators" such as cigarette smoking, high alcohol usage, high salt diets, and obesity should
also be determined.
Although the curable forms of hypertension rarely occur, tests for them should be
conducted. Differential arm and leg blood pressures and a careful search for chest murmurs and
rib notching on chest X-ray are needed to eliminate coarctation of the aorta as the cause of
hypertension. The results of a 24-hour urine test for catecholamines are important in evaluating
the possibility of a pheodhromocytoma, and a search for an abdominal bruit and a rapid
se(lumce I?P itt the diagnosis of renal aifery stenosis. Adrenal and thyroid evaluations
should also be done, however, a reriin level determina^oM usually adds littie information and is
difficult to perform accurately in an outpatient situation. ' , .
Therapy for essential hypertension is multifaceted. First, the patient, who may be totally
asymptomatic, must be educated about the risk of hypertension. Secondly, the hypertensive
risk factors noted above must be minimized. Finafly, drugs can he administered, not as a cure,
5-36
Internal Medicine
but rather as a controlling maneuver to lower cardiovascular risk. As far as vn Hilary aviation is
eoncerned, iiypertensive individuals may fly providing that they have no deteclaijie hypertensive
damage, and that their resting blood pressure is maintained below 138/88 mm llg with itotMhg
more than a thiazide diuretic (hydrochlorothiazide, 50 mg q.d. or b.i.d.). Alpha methyldopa,
guanethidine sulfate, and reserpine are not acceptable in military aviation because of their
orthostatic and CNS effects. Propranolol and hydralazine may be potential adjuncts for the
Flight Surgeon m the future, but they still require extensive evaluation in the aviation
environment under controlled circumstances.
Arteriosclerotic Heart Disease
The problem of arteriosclerotic heart disease (ASHD) is one of immense proportions, in that
the prevalence, incidence, and socioeconomic significance of ASHD or coronar\ artery disease
(CAD) exceeds the totaL of the next five leading causes of death and disabilit)'. By thetimPTpi
its clinical manifestation, arteriosclerotic heart dasease is generally a "late stage" disease.
Obviously, it is much better to attempt to control this disease prior to clinical masfetation.
Primary risk factors to be considered in any control program include the following:
1. Age
2. Sex ■ ' ■" '
3. Hypertension*
4. Smoking*
5. Elevated Serum Cholesterol*
6. Elevated Serum Triglycerides
7. Elevated Serum Glucose
8. Heredity
9. Personahty Factors (aniS Emotional Stress)
10. Obesity '
11. Carbon Monoxide Exposure.
*Each represents a threefold risk factor.
In addition, there are as many as 52 secondary risk factors which have been discussed by
investigators. It is apparent that prevention and control of arteriosclerotic heart disease can be a
complicated issue. ' "
The prevention of arteriosclerotic heart disease is a two-stage process. Theiprnftaay program
attempts to prevent the. Wtial appearance of the disease. This is where a Flight Surpoil mn
make an excellent contribtition through a program of discussions with flight personnel
5-37
U.S. Naval Flight Surgeon's Manual
concerning the controllable risk factors underlying the disease. A secondary phase attempts to
prevent the progression of the disease once it has been identified. Here, standard cardiac support
procedures are usitj, £©4 # is lem Kkely that a Flight Surgeon will be directly involved.
Anginit Pedtotis
Angina pectoris, in its classic form, is substernal "crushing" or "vice-like" chest pains which
iQ^ radiate into the neck, left shoulder, left ann, and left hand. The pain responds to rest or to
nitro^ycerine administration. Althou^ Heberden described the symptom complex of angina
some 200 years ago, studies during the past 20 years have seen a progressive increase in the
number of variants now recognized. For example, the pain may radiate to either shoulder, arm,
or hand; it may radiate to the interscapular area of the back; it may radiate to the epigastrium.
In other instances, angina may not take the form of pain at all, but may be experienced as
%spnm on ^xeliiofa, the so-called "angina equivalent," Comnlon physical fittdings during
angina include pallor, diaphoresis, tachyciu-dia, hypertension, % gdlops, and apical systolic
murmurs (papillary muscle dysfunetibn). The resting EGG is helpful for identification only if it
is positive for ischemic changes.
Exefcise testing "is useful for establishing a diagnosis of angina pectoris if the patient's
symptoms and/or response to therapy leaves some doubt about the initial diagnosis. In
correlating exercise stress testing with angiography, the following conclusions can be drawn:
1. Stable or accelerated angina has a 70 percent chanjje of diowing obstruction (probably
greater than 80 percent) in at least two major arteries,
2. Resting angina is associated with a greater than 80 percent obstruction of long segments
of the RCA.
3. False n^ative or equivocal tests are frequently associated with RCA or CCA disease.
4. An ST depression of greater than 2 mm implies obstruction of the proximal LCA and a
critically narrowed RCA.
5. Prinzmetal angina is likely to have a single vessel critically narrowed, commonly the LAD,
The five-year survival rate for significantly narrowed I, U, and HI coronary artery
involvement is 95, 75, and 50 percent,, r^spectiyfjly.
Treatment of Angina Pectoris
The management of this condition is through drug administration. The oxygen content of
eoroimy aiierial Jilojod an4 «Xf^n extraction by the heart is maximal under almost all
conditions. Therefore, the only mechanism for^augmentation of myocardial oxygen supply is an
increase in coronary flow. Coronary flow normally increases with coronary dilation. It also is
5-38
firtemal Medbine
greatest during diastole. Conditions for improving coronary flow can be. obtained with
dmgs, as shown in Table 5,-7.
Table 5-7
Action of Common Medications in Treatment of Angina
Nitrites
|3-Blockers
Contractility
Reflex f
Heart rate
Reflex f
4
Systolic watt stf^
VentriGlB diameter
Systolic pressure
i
Nitrites relieve angina by dilating venules and arterioles. Venous dilation resiidls in decreased
venous return with a decrease in heart size and stroke volume. Arteriolar flilatiom reAices
systoUc pressure work.
Beta'Wockers represent a second class of drug useful in angina therapy. Beta-blockers
decrease oxygen demand by decreasing heart rate, the contractile state of the myocardium, and
systoUc pressure. -
There are other drugs and other procedures useful S the inanagement #f ategM pecl^ris.
Digitalis, in coexistent L¥ Mure, diuretics, with insipient failure and hypertension,
anti-arrhythmics, and antihypertensives can be beneficial. The patient can help himself by the
avoidance of physical and emotional stress, correction of obesity, and avoidance or reduction in
cigarette use, " r
Exercise Testing
The objectives of ejEerclse tefetSttg afe fourfold. These tests may be used 1» egtabUdi a
diagnosis in overt or latent coronpy arterf disease, to esPiduate eardiovasetilar fiinctional
cs^acil^, to ei^uate response to conditioning programs, and to increase motivation for entering
and/or adhering to exercise programs.
Multi-stage or graded exercise tests, with progressively increasing workloads, are &e most
effective mett^ib to teveH latent ischemic heart diSSase. The Masters test it tet costly, but also
less stressful sfA less standardized than graded exercise tests (GXT). The Brttcg protocol may be
followed, as described in Tables 5-8 and S-9.
5-39
Table 5-8
Pi-edicted Heart Rates for Various Age Groups with the GXT
o
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
Max H- R.
Untrained
197
195
193
191
189
187
184
182
180
178
176
174
172
170
168
^vTv ivi n n
177
17K
1 "71
1 //
T70
168
166
164
162
160
158
157
155
153
151
85%
167
165
165
162
160
158
156
155
153
151
149
148
146
145
143
75%
148
146
144
143
142
140
138
137
135
134
132
131
129
128
126
DV/7D
Ho
III
lie
1 IS
114
113
112
110
109
108
107
106
104
103
102
101
MaxH. R.
TfBined
190
188
186
184
182
180
177
175
173
171
169
167
165
163
161
90%MHR
171
169
167
166
164
162
159
158
156
154
152
150
149
147
146
8S%
161
159
158
156
154
152
150
148
147
145
144
142
141
139
137
75%
143
141
140
138
137
135
133
131
130
128
127
125
124
122
121
60%
114
113
112
110
109
108
106
105
104
103
101
100
99
98
97
ladipiMrfRMn Bruct. 19tl) .
Table 5-9
Bruce Protocol for Graded Exercise Testa
Stage
Speed
Grade
Minutes*
Rest
0
0
0
I
1.7 iftph
II
2.5 mph
12%
6
III
3.4 mph
14%
9
IV
4.2 niph
16%
12
V
5.0 mph
18%
15
VI
5.5 mph
20%
18
VII '
6.0
32%
21
Each stage is 3 minutes long,
(adapted from Bnice, 1971).
Certain cautiom shoidd be observed in deciding upon an ex.ercii^ test. Exercise testing is
superfluous and may carry unwarranted risks in patients whose symptom conipl^x su^ests
coronary angiography as a preliminary step to bypass surgery. Exercise testing also should not
be performed when a positive resting ECG already is present. Finally, in digitalis therapy,
exercise-stress testing is of no value since ST-T changes cannot be adequately interpreted. Also,
exercise testing in the face of left bundle branch block is of little informative value due to the
ST-T changes. Figure 5-28 shows various ST-T changes which may be obtained during
exercise testing. . '
A. Normal D. Ischemic ST segment depressitm (horizontal)
B, False junctional depression due to T;^ wave E. Ischernic ST depression
f. Ptiysiolagic ST segment depression F. Isolated T-wawe inversion
Figure 5-28. ST-T changes in ex^rcfse testing.
5-41
U.S. Naval Mi^t Smgeoix'e Manual
The risk of death during the 24-hour period following exercise testing is less than
1 in 10,000. The risk of nonfatal complications requiring hospitalization is 2.4 in 10,000.
Coronary Angiography
There are a number of reasons for recommending coronary angiography as a diagnostic
procedure, recognizing that it is a delicate technique. It can be very helpful in the following
cases:
1. Licapacitating angina unimproved by medical therapy in patients being considered for
surgical intervention
2. Angina in patients with CHF who are not responding adequately to medical therapy and
who also are being considered for possible surgical intsryention
3. Postinfarction complications such as aneurysm, perforated septum, and gross mitral
insufficiency
4. Ai^ina in young adults
5. Diagnosis of atypical chest pain
;6v Suspected congenital lesions of the coronary circulation
7. Asymptomatic patients with abnormal ECGs, especially in patients who may be
disqualified from insurance or from their occupations
8. Patients considered for valvular surgei^ at risk for concurrent coronary artery disease
9. As a means of evaluating results of surgical intervention.
The grading of lesions found during coronary angiography ranges from absence of
abnormahties to trivial irregularities to localized narrowing greater than 50 percent but less than
90 percent of the luminal cross section of a vessel. More serious grades include multiple
narrowing in the same vessel greater than 50 percent but less than 90 percent, narrowing of
greater than 90 percent^ and total obstruction without distal filling from proximal segments.
Scoring of the lesions is fipplied individually to each vessel.
The mortahty rate from coronary angiography is 0.5 percent, with a complication rate
ranging between three and five percent. Obviously, there must be carefully documented
requirements prior to the selection of this procedure.
Bypass Surgery
The current technique in bypass sui^ery is the use of a saphenous vein graft from the aorta
to a point distal to the occlusive site in a coronary artery with adequate "run-off." Bypass
surgery remains a controversial issue and should by no means be considered a panacea. However,
5-42
Intemal Medicine
angina unresponsive to medical therapy has a 75 percent chance of improvement with
revascularization therapy. Nineteen of twenty patients survive the procedure, and three of four
grafts are patent after one year. Still, one in four patients suatams an infarction on the day of
surgery.
The influence of bypass surgery on life expectancy has not as yet been well documented.
There are indications, however, that it is also useful in amelioration of CHF, papillary muscle
dysfunction, or arrhythmias.
Sudden Death Syndrome
Approximately 1,000 Americans die each day of heart attacks before reaching a hospital.
Sixty percent of the patients who die from infarction do so within one honr after onset of
symptoms. The highest risk grotip for sudden death includes those with known coronary artery
disease, 45 years of age or older, with hypertenaon, showing frequent ectopic beats, and with
unstable angina.
There is evidence that acute thromJms formation may not precipitate acute, fatal, ischemic
heart dise^e. The major probleiil appears to be diffuse, generalized coronary atherosclerosis
ydih greater than 75 percent luminal narrowing of at least two of the three major coronary
arteries.
Systems are under development to expedite a delivery of care to heart attack victims. There
also are current programs to train bystanders to provide emergency treatment (cardiopuhnonary
resuscitation) until professional care arriv®. Y#, jn oi^ #ttdy, 7f percent of toe who died
suddenly h«d instafttanepua^ unwitnessed, or rapid death. In the last case, the event occurred
while mobile coronary care units were being summoned.
Acute Infarction
Most patients suffering an acute infarction who reach the coronary care unit will survive.
The first 24 hours are largely used to relieve pain and anxiety, to establish the diagnosis, and to
treat arrhythmias. ReUef of pain is best aCBoMpiyied by morphine sulfate (ILSi). RnQphyiactic
anti-arrhythmic agents are effective in reducing the prevalenelof i^entlieular ectopics, feu# Aey
do not significantly reduce mortality when compared to rapid use of similar agents when
specific indications arise.
Diagnosis of acute infarction consists of a compatible history, ECG changes, and enzyme
changes. Generally, two of these three criteria are necessary for a positive diagnosis. The enzyme
changes to be found in acute myocardial infarction are shown in Figure 5-29. The problem of
5-43
U.S. Naval Flight Surgeon's Manual
false-positive enzymes has been largely circumvented by iso-enzymes of CPK and LDH. There is
evidence to suggest the CPK curve can be analyzed to give insight into the size of the infarction.
0 5 10 15
TIME IDAYS)
Figure 5-29. Enzyme curves in acute myocardial infarction.
In establishing a diagnosis, low risk patients are identified as those less than 65 years of age,
with an absence of CHF, an absence of advanced A-V block, rapid cessation of pain, and
nontransmural infarction.
In acute myocardial infarction, lieart failure occurs wlien there is sufficient injury to the
myocardium so that the heart is luiable to provide necessary cardiac output to meet tiie
metabohc needs of the body. Control of arrhythmias or correction of hypovolemia is often
sufficient to correct the low output state. The indication for antiebagalatioTi eeeihs to be as
prophylaxis for thromboembolic phenomenon in the patient at prolonged bed rest. The low
output, if sufficiently severe and if not due to a reversible cause, may lead to cardiogenic shock.
Mortality iu cardiogenic shock may be as high as 90 percent.
If available, intra-aortic balloon counterpulsation may be of value, as may be surgical
intervention. However, these techniques are still in the experimental stage and are not
universally appUcaMe, nor available.
Aviation Personnel
Ischemic heart disease simply is incompatible with naval aviation. Exposure of the patient
with significant coronary artery disease to the stress and potential hypoxic environment of the
aviator is an invitation to disaster. The element of risk to the aviator, the crew, the aircraft, or
5-44
Internal Medicine
potential victims on the ground cannot be justified by any rationale. Even the asymptomatic,
postoperative coronary artery bypass patient has the risk of sudden death while in flight. The
same risk likely applies to those aviators who have survived an acute myocardial infarction.
Stated policy is to permanently ground any aviator with known ischemic heart disease.
Acquired and Congenital Structural Heart Disease
Structural disease of the valves and waUs of the cardiovascular system can present to the
Flight Surgeon in a variety of ways. A new murmur, a subtle 1£G fmding, or a iuspicious x-ray
inay be the iRrst clue. Conversely, a well-doeumented hskm that may or may not have had
surgery in%ht be the presenting factor. Structural defects and aviation are not necessarily
incompatible. Knowledge of the current cardiovascular status and the natural history of the
lesion, particularly with regard to the risk of sudden incapacitating arrhythmias, is essential to
intelligent management. A good history, physical examination, ECG, and cardiac series coupled
with an exercise ECG can give an excellent assessment of current function. Specific diagnoses,
however, usually require eGhocwdiography qr eardiae calhetiBjcization. The 24-hour ECG
mernitoring tape is also useful for egtabUshing aiarhythjnia risk, Tha patient's ftiture in aviation
will depend on the demonstration of normal cardiovascular function, a low risk of eventual slow
decompensation, and virtually no increased arrhythmia risk over the general population. Several
of the more likely defects to occur in the otherwise healthy, young adult deserve further
comment.
Functional (Imu ::ent) Murmurs
These murmurs, by definition, do not represent cardiac defects, but differentiating them
from true diseases can be difficult. The classical functional murmur is a low-frequency, musical,
or buzzing murmur, less than II/VI in intensity, appearing in early to mid systole and localized
to the left sternal border. There must be no diastolic component, and the second sound must be
normally split. Such a murmur presumably represents blood flow across the pulmoiuc valve and
is more common in slender, athletic individuals.
An innocent systolic murmur with characteristics similar to the above has been described at
the cardiac apex. Special care must be taken to differentiate it from mitral murmurs,
particularly the mitral prolapse syndrome.
Congenital Shunts
Septal defects at both the atrial and ventricular level patent ductus arteriosus are the
most common shunts that may be present in a seemingly fit young adult. Any of the three may
present de novo, if small, or may be many years postsui^cal repair.
5-45
U.S. Naval Fli^t Surgeon's Manual
Stnall atrial septal defects may go throu^ a normal Hfespan and be detected only at
autopsy. The Flight Surgeon, however, may detect them in the course of a workup for a systolic
murmur, right bundle branch block, or a fuEness to the right ventricle or pulmonary artery on
x-ray. The characteristic, widely split second sound and right ventricular erdargement solidify
the diagnosis. Cardiac cathetemation is always indicated, md all but the smallest defects dhould
be closed. Nonnal rl^t ventricular and pulruoiiaiy artery pre^res postsuigeiy carry an
excellent prognosis, but the small increased risk of supraventricular tachycardias probably
disqualifies from military aviation.
Ventricular septal defects (VSD) are usually diagnosed in infancy. Moderately large shunts
that are repaired in childhood with normal intracardiac pressures postsurgery have an excellent
pro^osis, but, agfidn, the small arriiylliinia risk probably disqualifies from an aviation career. A
dli^t VSD in the asymptomatic child progressively becomes smaller as the child grows and thus
may present in the young adult as only a positive history with or without a systolic murmur.
The natural history of this lesion is virtually normal and thus is compatible with military
aviation. Nevertheless, a complete, normal cardiovascular examination including 24-hour ECG
monitoring, is needed. Subacute bacterial endocarditis (SBE) prophylaxis is also indicated in
these patients,
A patent ductus arteriosus surgically corrected in childhood with normal cardiovascular
function one year postsurgery has an excellent prognosis and presents no contraindication to an
aviation career. The small ductus that remains undetected and asymptomatic until young
adulthood is rare. In these patients, pulmonary plethora, left ventricular enlargement, or a
continuous high frequency murmur under the left clavicle may suggest the diagnosis. The chest
X-ray may show the ductus as a convexity between the aorta and the pulmonary artery. A
catheterization is always indicated. If the shunt is small (less than 1.5:1) and aU pressures are
normal, the prognosis is generally excellent, although SBE prophylaxis is indicated. These
people may quahfy for aviation. Large shunts require surgery, and the decision to pursue a
career in aviation should be defeired until at least one year postsurgery.
Congenital Valvular Malformations
Mild stenosis of the pulmonic valve is consistent with near normal ^owth, virtually
symptom free, carrying only the diagnosis of "functional murmur." However, mild exercise
intolerance, evidence of right ventricular enlargement on physical examination, large anterior
R-waves on ECG, and poststenotic dilation on chest X-ray should make one suspicious of the
diagnosis. , Cardiac catheterization is necessary for full evaluation. Since normal right ventricular
pressures are mandatory for mihtary aviation, individuals with this uncorrected malformation
are generally disqualified. Surgery with near nonnal postoperative pressures is associated with
5-46
Internal Medicine
excellent results, but, again, the small arrhythmia risk probably disqualifies the individual
from an aviation career.
Congenital aortic stenosis, though often with a more benign prognosiB than its rheumatic
counterpart, still has risk of eventual myocardial dedcatipeEaation and arrhythmias Ihat is
unacceptable for aviation.
The bicuspid aortic valve is a very common congenital abnormality, and often its diagnosis is
not made until young adulthood or later. The natural history is for the lesion to be functionally
normal for many years with only an incidental aortic flow mUEmur or regu^gitani.HttUtniiW. The
approach is to confirm the normal eardiovaseular function by noianyasiw m^am md
prophylax for SBE. Although there is no eonteaindication to flying, these individuals should bp
followed carefully since calcified stenosis or significant regurgitati#l ms^ develop over the years
and produce symptomatology. ...
Coarctation of the Aorta
A coarctation is usually diagnosed in the pediatric population, but occasionally a mild one
will not be detected until yoxuig adulthood. Upper body hypertension, the systolic murraur that
radiates to the back, rib notching on chest X-ray, and evidence of left ventricular enlargement
me the presenting signs in the adult. Additionally, bicuspid aortic valves and Berry aneurysms
are associated with coarcts. Th<; disease is progressive and surgery is almost always indicated. In
spite of possibly excellent hemodynamics postsurgery, patients with coarcts have an increased
risk of intracranial hemorrhage, eventual hypertension,, and acc^erated eorongry artery dl8ea§0.
Thus, their place in military aviation is limited, and most, if not all, should be disqualified,
Rheuia^ Valvidflr Dmeasie
Valvular dysfunction on a rheumatic basis, even if mild, is associated with an increased risk
of arrhythmias, cardiac failure, and emboli, and thus is disqualifying. Valve replacement, though
often of great benefit hemodynamically, is inconsistent with a career in military aviation. A
history of acute rheumatic fever (ARF) without evidence of valvular dysfunction is not
disqualifying. Penicillin prophylaxis against recurrent ARF is also not disqualifying.
Mitral Proline Syndrome (Hoppy Mitrid SyAdrotoe, Cfick-Muimur Sytidfome)
This is becoming an increasingly recogmsaed syndrome, particularly in young adults. It
consists of a myxomatous degeneration of the mitral valve resulting in its prolapse into the atria
during systole. This produces the characteristic mid systoUc click and late systolic mitral
regurgitation murmur that is often the' only sign of the disorder. The diagnosis is readily made
5-47
U.S. Naval Fli^t Surgeon's Manual
by echocardiography. The vast majority of patients with this syndrome appear to have a benign
prognosis, although SBE prophylaxis is indicated. A small percentage do have risk of
arrhytlunias, and these individuals should be disqualified from aviation. They can usually be
identi§«d by a history oi arsbythmias, nonapeeific ehMt pains, and ST- and T-wave
abnormalities on their EGG. Exercise testing and 24-hour EGG monitoririg should be done on all
aviators with this condition to rule out an arrhythmia risk.
Idiopathic Hypertrophic Subaortic Stenosis (Asymetrical Septal Hypertrophy)
This is a bizarre pathologic hypertrophy of the septum of the heart just below the aortic
valve. The etiology is uitkilowii but often first pFesents in young adultiiood. Initially, an aortic
stenogas'type murmur may be fJie only itgn. This toUifltiur characteristically increases with the
Vais#r4 maneuver f^ch decrea^s left vettteicular filMng and worsens the obstruction.
Symptoms of exercise intolerance from outflow obstruction or arrhythmias may be present.
Echocardiography usually will demonstrate the hypertrophied septum. Although the disease
may have a long, benign course, the risk of arrhythmias and progressive cardiac decompensation
are disqualifying for aviation.
Endocarttitis and Endocarditis Prophylaxis
hiflammation of the endocardium usually has an infectious basis and frequently occurs on
the valve surface or on various congenital defects. It is felt that only damaged valves are
susceptible to infection, but frequently the damage is not recognized prior to the infection.
Fever and new or changing heart murmurs (particularly diastolic murmurs) are the hallmarks of
endocarditis. Unexplained anemia, emboli, and a variety of immune phenomena are common.
Diagnosis should be confirmed with applfofiriate blood cultures. Therapy requires hospitaliza-
tion and intravenous antibiotics. Return to flight status requires a normal cardiovascular
examination including an zeroise test and 24-hour EGG monitoring for arrhythmias.
Prophylactic antibiotics for people with defects at risk of endocarditis (e.g., bicuspid aortic
valve, floppy mitral valve) should be given during periods of potential bacteremia. Such
prophylaxis is not a contraindication for flight status. Gurrent recommendation for dental work
is oral penicillin, 600,000 units, two hours before procedure and q.i(i. for 72 hours thereafter.
Erythromycui, 250 mg or a similar dosage schedule, may be substituted in those patients
sensitive to peniciBin, For GI or GU procedures, procaine penicillin, 1.2 million units, I.M.
should be given one hour before procedure and q.i.d. thereafter for 72 hours. Streptomycin,
0.5 g I.M. q.l2 hours should also be given for GI and GU procedures.
548
Internal Medicine
Principles of Cardiopulmonary Life Support
Generally speaking, the sustainment of life requires continuous oxygen delivery and a near
normal pH. These requirements in turn, depend upon (1) delivery of oxygen to the lungs, (2) an
adequate circulating blood volume, (3) an adequate pump, and (4) an appropriate buffer
system. In a cardiopulmonary emei^efi<gr, theie ptinciples must be remcmbetesd, and their status
should be known at all times.
Oxygen Delivery
Mouth to mouth ventilation, if given properly, gives five to ten liters per minute of
16 percent oxygen to the victim. This is adequate for maintaining life-sustaining oxygenation.
Methods to maintain a patent airway include extension of the neck, which pulls the tongue
forward off the posterior phwynx, oro- and nasopharyngeal airways, esophageal airways, and
endotracheal tubes. Obstructed airways can be manually cleared, opened by the Heimlich
maneuver or blows to the back, or bypassed by using a cricothyroidotomy. An Ambu bag can
be attached to either a mask or a tube for assistance in the delivery of oxygen.
' ' i Circulating Blood Volume
Par^cularly in trauma where hemorrhage may be a major problem, blood volume
monitoring will be critical. Neck veins are useful, but a central venous Une or Swan-Ganz
catheter should be used whenever possible.
Circulation Pump
External cardiac compressions, if done properly, will produce adequate stroke volumes for
prolonged periods of time. Dysrhythmia management is discussed elsewhere, but it should
always be ^ven m Conjunction with these life support maneuvers. Indeed, hypoxia and acidosis
are the most common cause of dysrhythmias refractory to drug therapy. If a reasonable rhythm
is present but little or no pulse is obtained, one should think of a pericardial effusion, severe
metabolic disturbance, or hypovolemia. The best pressor is dopamine given in an I.V. drip of
5 to 50 micrograms/kg/min.
Acid/Base Balance
Acidosis rapidly develops with hypoxia. AlthQU#i arterial blood gases are the ideal way to
haindle pH disturbances, a general rule of Hmmh to follow during a cardiac arrest is to give
1 mEq/kg of HCO3 I.V., initially. This dose is repeated ten minutes later, and then half of this
dose is given q. ten minutes thereafter.
549
U.S. Naval flight Sui^eon's Manual
The American Heart Association and the American Red Cross have nationwide programs to
certify all interested people in basic life support techniques. It would be appropriate for all
night SurgeonSi to not only be certafiiejd but also aMe to conduct courses for corpsmen sad
other ipepraonnel. These techniques diouid, furthermore, be rehearsed on a routine basis. The
Flight Surgeon should be comfortable with equipment and drugs necessary for cardiopulmonary
life support. Advanced Life Support certification by the American Heart Association for all
Flight Surgeons is to be encouraged.
Peripheral Vascular Disease
The circulatory system's major function is that of providing blood flow adequate to meet
tissue needs at rest and with exercise. Vascular disease of the extremities impairs this function.
It commonly develops as a result of degenerative processes, hence, the incidence increases
progressively with age.
The vascular supply of the loWter eSctremities can best be visualized as a U^^aped eircuit.
Tha aorta and large arteries form one arm, the larger venous channels and vena cava form the
opposite arm, and the small vessels form the interconnecting member. The system is filled with
blood, and with each cardiac contraction, the amount of blood entering the system equals that
being discharged. In the erect position, pressure in the bottom qt the "tl'" is increased by the
effect of gravity on the column of blood. The equilibrium between Hydrostotic and colloid
osmotic pressure is thereby unbalanced, leading to fluid "seepage" across the capillary walls into
the interstitial spaces. Some edema forms in normal patients, but this is counteracted by the
effective venous pumping mechanism of the calf muscles and the valves of the femoral venous
sy^em.
Venoqa Insufficiency
If die valves of the femoral ^stem become incompetent, blood pumped out of tiie leg hf
muscle action returns immediately when the muscle relaxes. Tissue oxygen falls with decreased
flow, and edema formation leads to tissue damage. Ulceration and necrosis may eventually
develop. Signs of dark pigmentation, edema, and scaling of skin about the ankles become
prominent.
Arterial InsuMciency
Pain is usually the first symptom of arterial insufffoiency.' It cajo be accoinpfflaied by
intermittent claudication and is relieved by rest; it is b^t njeasuted 'm the c^istanee iJle patiiEsnt
can walk before pain causes him to pause for relief. Arterial disease can be suspected when the
pain is influenced by posture, when it is localized to one digit, or when it is paroxysmal
5-50
Intenuil Medicine
in nature. As vascular insufficiency increases, pain may be present at rest and relieved
when the limb is dependent.
Normally, there is sufficient blood flow to prevent pallor of the digits when the affected
Bmb is raised. Delay or failure of color return when the patient Iqwcts the extremity is
indicative of arterial obstruction. Blushing should occur immediately, suld, if not apparent
within 20 seconds, severe obstruction without adequate collateral circulation is present.
Venous filling time is the time required for an empty vein to fill on sudden dependency
following elevation (when valves are intact). Failure of the vein on the doraim of the foot to fill
within SO seconds usually indicates inadequate arterial flow.
Diminished pulses may also indicate arterial disease. Dorsalis pedis pulses may be
congenitally absent in ten percent, whereas the posterior tibials are absent in only two percent.
Atrophic changes develop as arterial disease progresses. The skin becomes dry, atrophic,
shiny, and tightly drawn, with loss of hsur. Nails become hard, thickened, and ri^d, and minor
trauma may result in ulceration.
Ischemic Peripheral Vascular EHseases
Occlusive disease of the peripheral arteries may be due to organic obstructive disease or to
an angiospastic disorder. EmboHsm, arteriosclerosis obliterans, Buerger's disease, and Leriche's
syndrome are the main causes of ischemic symptoms in the legs. Ischemic manifestations in the
upper extremities are usually the result of Raynaud's disease, Buerger's disease, embolism, aortic
arch syndrome, or thoracic outlet syndrome. Clinical manifestations are related to the rapidity
with which obstruction occurs and also to the rate at which collateral circulation develops.
Arterial Embolism. This problem illustrates acute vascular ischemia. Over 90 percent of
these emboli originate in the heart, with rheumatic heart disease and ASHD each accounting for
40 percent of cases. In 40 to 50 percent of cases, atrial fibrillation is present.
Emboh lodge in the lowesr extremities more frequently tiian in the upper extremities.
Embolectomy is indicated when sensory dysfunction and motor loss progresses above the wrist
or ankle. Heparin therapy should be initiated as soon as possible to prevent propagation of the
thrombus.
Arteriosclerosis ObUteram. Progressive, chronic ischemia is illustrated by this entity. The
onset is between 50 and 70 years of age in the non-diabetic and 10 to 20 years earlier in the
5-51
U,S. Naval Fli^t Surgeon's Manual
diabetic patient. The pathognomonic symptom is intermittent claudication; loss of pulse in the
legs and feet is the most common sign.
Conservative treatment includes meticulous cleanliness of the involved extremities,
avoidance of trauma, cessation of Smoking, elevation of the head of the bed, and exercise to
encourage development of collateral circulation. Vasodilator drugs are of doubtful usefulness.
Lumbar sympathectomy may be helpful in relieving rest pain and minor ulceration.
Reconstructive arterial surgery or grafting procedures are indicated when conservative measures
fail. Long-term aortoiliac grafting results have been gratifying (greater than 80 percent patency).
Fifty percent of femoropopUteal bypass grafts close vrithin one year, however, and a saphenous
vein bypass graft is superior.
Buerger's Disease. Throm go angiitis obliterans involves the arteries of intermediate and
smaller size, resulting in more distal occlusions than arteriosclerosis obliterans. Onset is most
often before age 40, and the disease may begin in teenagers. Almost all presenting patients are
males with tobacco-smoking histories. If the patient stops smoking, arrest of the disease is the
rule. Multiple amputations may be required if the patient continues to smoke.
Leriche's Syndrome. Aortoiliac occlusive disease results from obstruction of the abdominal
aorta and its main branches by atherosclerosis. The pain associated with Leriche's syndrome is
commonly gluteal, and there may be sexual impotence.
Angiospastic Disorders. Peripheral vasospasm may be a normal peculiarity in certain
individuals, exaggerated by cold, tobacco, anxiety, and menopause. Raynaud's disease shows
digital ischemia (paroxysmal) triggered by cold, emotion, or tobacco; there is no evidence of
obstruction of large limb vessels. Raynaud's phenomenon is often applied to vasospastic
episodes associated with organic vascular disease, e.g., thromboangiitis obliterans, progressive
systemic sclerosis, polyarteritis, systemic lupus erythematosus, polycythemia, cervical rib
syndrome, etc.
In general, any of these disorders are disqualifying for flight unless corrective measures (e.g.,
endarterectomy with restoration of normal circulation) can be taken prior to onset of
irreversible changes.
Peripheral Venous Disease. Deep vein thrombosis of a tower extremity is the common
source of pulmonary emboli. Clinical situations which predispose to thrombosis in the lower
extremity include postpartum state, postoperative state, CHF, trauma, and prolonged
inactivity as in the postmyocardial infarct period.
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Internal Medicine
Tenderness in the calf muscles on palpation or dorsiflexion (Homan's sign) are useful for
detection of sural (calf) venous thrombophlebitis, but the absence of this sign does not exclude
the disease.
Tht cuff-pain test may be useful in the diagnosis of early thrombophlebitis. A blood
pressure cuff is placed around the involved part of the extremity and is slowly inflated to
20 mm Hg. In venous inflammatory disease, the patient will indicate pain at lower levels (60 to
150 mm Hg).
Anticoagulant therapy (I.V. heparin) should be initiated immediately to prevent extenaioii
or release of the thrombus. Recent studies show elastic stockings to be of no value in prevention
of deep vein thrombosis, whereas active and passive exercise of the legs at regular intervals is of
value in those patients at prolonged bed rest. Early ambulation is recommended, but obviously
cannot always be achieved. If recurrence of pulmonary embolization is a problem, venous
ligation or plication may be indicated.
In chronic problems with varicose veins, aching, discomfort, edema, dewnatitis, and stasis,
ulceration may be a complication. Elastic stockings may help, but increased hydrostatic pressure
must be relieved by saphenous division and stripping and by division of any communicating
veins responsible for reflux.
5-53
U.3. Naval Fii^t Siirgeoti's Mannal
SECTION H: GASTROENTEROLOGY
Esophageal Reflux and Hiatus Hernia
Suffice it to state that the presence of a hiatus hernia does not necessarily result in
esophageal t^ii^i; neither does esophageal reflux necessarily require the presence of a hiatus
hernia. There is a growing and convincing body of evidence to support the idea that gastric
reflux into the esophagus is related to lower esophageal sphincter tone.
The lower esophageal sphincter (LES) is some 38 to 42 cm beyond the incisors, and,
although there appears to be little anatomical distinction from adjacent esophageal structures,
the LES normally pro'wdes m effective barrier to gastric contents.
Signs and symptoms of esophageal reflux include heartburn, waterbrash, chest pain (on
occasion, similar to angina), recurrent hoarseness, nocturnal dyspnea, and recurrent pneumonia
or lung abscesses.
Diagnosis may be made on the basis of history alone, in some instances. Direct and indirect
mefliods may be undertaken to prove reflux. Reflux may be desnonstrated by UXi.I. or by
endoscopy. Measurement of esophageal pH or the add perfusion test also may be used.
Castell (1975) reports in detail about the lower esophageal sphincter. Table 5-10 outlines
agents which, either increase or decrease LES tone.
Table 5-10
Agents Producing Change in LES Tone
Increase
Decrease
Gastrin/Pentagastrin
Secretin
Norepinephrine
Cholecystokinin
Bethanechol
Isoproterenol
Edrophonium
Phentolamine
Gastric Alkalinization
Atropine
FVotein Meal
Caffeine
Fatty Meal
Chocolate
Smoking
Ethanol
The effect of agents which increase LES tone is to decrease the potential of reflux; agents which
decrease LES tone increase the potential of reflux.
5-54
Intemal Medicuie
Thwapeutic considerations incMisi restrictioii of tsitty foods, chocolate, coffee, smoking,
and ethanol. Gastric alkalinization is the mainstay of therapy, however, and antacids have a
twofold place in therapy. First, antacids neutralize gastric acid and reduce esophageal irritation;
additionally, they increase LES tone, thereby reducing reflux.
With successful eemservative management, LIS tone should increase, thereby offsettittg the
potential for reflux in flight (under eonditioii8 of positive G-forces). In instances where
conservative therapy fails, however, marked increases in intra-abdominal pressure (e.g., Valsalva
maneuver while pulling G's) may lead to esophageal reflux; under conditions of positive pressure
breathing, this could be catastrophic. Therefore, disposition of the aviator in this condition is
dependent upon his response to therapy, as well as the type of flying being done. Certainly, the
VP amtior with reflux is at less risk than t^©,E44 pEot.
SuccessM surgical correction with newer antireflux procedures would obviously return the
aviator to an "up" status. Simple repair of a hiatus hernia, however, produces disappointing
results in a large percentage of patients; the newer procedures involve displacement of distal
esophagus below the diaphragm with an associated fundopUcation. Any surgical referral,
therefore, must be written with this in mind.
' PepMe Ulcer Disease
The incidence of peptic ulcer disease (PUD) rose rapidly from 1900 to 1950, but it has been
on the dedine since. Symptoms of PUD are pain which tends to be relieved by food, milk, or
antacids and which tends to show periodically with exacerbations during the spring and fall.
CompUcations include hemorrhage and perforation, and obstruction diagnosis of PUD depends
upon demonstration of an ulcer on U.G.I, or by endoscopic examination. X-ray evidence of
deformity of the duodenal bulb or the presence of spasm represents indirect evidence of PUD.
G^tKlft afialysis and serum gastrin levels also play a role in patient evaluation, but they are
and^siy studies and not necessari(.y diagnostic.
Therapy is centered around antacids at present, with hydrogen ion receptor antagonists
(e.g., cimetidine) holding future promise. Antichohnergics are ancillary, not primary,
therapeutic compounds. Diet is presently a controvBr8i4 isswe, with foeus of attention
having been the value of the classical hourly feedings combined with antacids on the half-hour.
Antacids, alone, appear to provide similar results. Caffeine, alcohol, and cola drinks should
defmitdy be restricted, as should smoking during the acute phase. Intractability is the most
common indication for surgery. Factors involved in making the decision to operate include
(1) PUD of more than 10 years, (2) marked duodenal bulb scarring with or without fistuUzation
or extraduodenal air-fluid level, (3) nocturnal pain of recent onset, (4) back pain of recent
5-55
U.S. Naval Mi^t Sui^n's Manuid
onset, (5) failure of antacids to relieve pitfn, ^6) ii^breadng duration aftd "frequency of
exai^Mijnft, and (7)TMet area of pain radiation. M'^^i^H im^f^ i^^ees of posterior
perforation. '. . '.
During the acute phases, the aviator should be grounded. Intermittent symptoms, relieved
properly by antacids, milk, or food, the last being a controversial item in therapy as previously
noted, may be anticipated and should be of little concern utiless a distiitet change in the pattern
is observed. Recurrent hemorrhage is viewed as a disqctidQfyin^ diajpdsis dno0 abrupt, masiave
hemorrhage can be debilitating and potentially fatal. A slow, chronic blood loss from the G-I
tract can be undetected for long periods, resulting in poorly compensated anemias.
Postoperative patients must be viewed on an individual basis, dependent upon results and
presence or absence of sequelae from gagMc surgery (e.g., dumping syndrome, afferent loop
syndrome, postvagotomy diarrhea).
Inflammatory Bowel Diaease
In Spiro's Clinical Gastroenterology (1970), a graphic review covers the salient points of
differential between ulcerative colitis and Crohn's colitis. Table 5-11 outlines the distinctions
between these two most common forms of inflammatory bowel disease.
Either diagnosis is permanently disquaUfying for aviation. The one possible exception is
ulcerative proctosigmoiditis. Farmer and Brown reported on 276 cases of proctosigmoiditis in
1972 and suggested that the disorder constitutes "the benign end of the spectrum of... ulcerative
colftis." Progression to ulcerative pancolitis occurred in only ten percent, and progression took
place mpm the itist three years fgllowing diagnosis. Hyi&ocoFtisone enemas provided a
satisfajs^ry therapeutic approach. Systemic complications such as toxic coKjis or colonic
carcinoma were rare.
Li any event, each case of ulcerative proctosigmoiditis must be individually considered.
Follow-up by gastroenterology or internal medicine services must he available, and assignment
to isolated duty stations should not be advised. Fmquent recurrences, systemic symptoms, or
progression of the disease on barium enema would provide justification for permanent
grounding. Either a Local Board of Flight Surgeons or the Special Board of Flight surgeons
should review individual cases and make appropriate recommendations to the Bureau of
Mediehtd.
Hepatii; Disordeis
Viral hepatitis is covered in the section on infectK)US diseases. Discussion will be hmited
under this topic to Gilbert's syndrome, Dubin-Johnson syndrome, and alcohol-induced hepatic
disorders.
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Internal Medicine
Table 5-11
Distinctions Between Ulcerative and Crohn's Colitis
Ulcerative Colitis
Crohn's Colitis
Toxicity
Common
Rare
Bleeding
Common, but minor
Rare, but massive
Perianal Disease
Rare
Common
Perforation
Rare, but into peritoneal cavity
Not uncommon, but
corrfined
Sigmoidoscopic
Diffuse granularity and
Discrete ulcers in normal
Findings
ulcerative > 95%
mucosa, 30%
Cancer Potential
Greater than norrnal
No difference f rorn
normal
X-ray Findings:
Rectal Involvement
Usually
Not common
Distribution
Continuous with rectum
Segmental, patchy
Mucosal Appearance
Granular, shaggy
Fissures, deep ulcers,
cobblestones
Ileum
Backwash ileitis, 10%
Regional ileitis, 30%
Strictures
Rare
Common
Fistulas
Rare
Common
(adapted from Spiro, 1970).
Gilbert's Syndrome
Gilbert's consists of mild unconjugated hyperbilirubinemia (usually 3 mg %) without either
hemolysis or excessive bilirubin production in generally healthy patients. Hyperbiiirubinemia
may be intermittent and accentuated during iUness and during periods of fasting. Liver function
Studies are normal, and biopsy tissue excludes the diagnosis of hepatitis since histology is
entirely normal. Phenobarbital and other drugs which induce the microsomal enzyme systems
will lower serum bilirubin. Patients with Gilbert's are physically qualified for aviation.
Dubin-Johnson Syndrome
Dubin-Johnson's is a familial disorder caused by impaired hepatic excretion of certain
organic anions into the bile. Jaundice is intermittent and is often associated with l^t upper
quadrant abdominal pain and cojijugated hyperbilirubinemia. BSP retention at 45 minutes is
normal, but due to impaired bilary excretion, the two-hour level exceeds that seen at
45 minutes. Alkaline phosphatase is normal. Liver biopsy confirms the diagnosis by disclosing
the presence of black tissue on fresh liver biopsy specimen. Microscopically, melanin-Uke
deposits are present in the centrilosular areas in parenchymal cells. The disorder is benign and is
not considered disqualifying for avia,tion.
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U.S. Naval FH^tSiifgeoil's Manual
Alcoholic Liver Disease
Aleokol is metabolized almost entirely within tiie liver. Alcohol is initially attacked by the
alcohol dehydrogenase system which is the main pathway in the non-abuser. In the chronic
alcoholic, the microsomal ethanol oxidizing system clears 50 to 67 percent. The catalase system
is a relatively minor route of ethanol degradation. Alcohol, in part due to stimulation of
microsomal enzyme systems, produces mild hyperhpidemia; triglycerides, cholesterol, and
ketone bodies accumulate.
Fatty liver due to alcohol abuse, althou^ not an inflammatory change, per se, shows certain
changes on electronmicroscopy indicating a continuum with alcoholic hepatitis. Damage to the
hepatocyte from ethanol ultimately leads to alcoholic hepatitis, the histologic hallmark of
which is the Mallory body (paranuclear hyahn). Through necrosis and inflammatory changes,
scarring and ciniiosis afe ultimately seen. Central hyalin sclerosis appears to brii^e the gap
between hepatitis and cirrhosis.
Alcoholic hepatitis is the clinical syndrome of fever, leukocytosis, and ascites in the face of
abstinence from alcohol. Although a small percentage may completely recover, this is not the
rule. The incidence of continued hepatitis and/or cirrhosis is greater than 80 percent.
Hepatocelluhu- dysfunction induced by alcohol abuse, if sufficiently advanced to result in
fatty infiltration, is justification for grounding of the aviator. It must he stressed, however, that
more timely methods of alcohol abuse detection should be employed by the Flight Surgeon;
this topic will be discussed in Chapter 19, Alcohol Abuse.
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Internal Medicine
SECTION ni: HEMATOLOGY
Anemias — An Oveiriew
Due to the vast scope of this subject, the reader is referred to standard medical texts and
hematology references for detailed studies of specific hematolo^c topics. A basic classification
of anemias wiU be outlined herein as a general diagnostic aid.
Morphologic classification of anemias is a simple method which directs further investiga-
tional study. Three formulae devised by Wintrobe (1932) are utilized in determining cell size
and hemoglobin concentrations:
Mean Corpuscular Volume (MCV)
(in cubic microns, cju)
Mean Corpuscular Hemoglobin (MCH)
(in micromicrograms, 77)
Mean Corpuscular Hemoglobin
Concentration (MCHC)
(in percent, %)
The above values can be determined on the basis of results provided by a complete blood
count (hemoglobin, hematocrit and red blood cell, white blood cell, reticulocyte, and platelet
counts).
Table 5-12 provides an outline for the morphologic classification of anemias to aid the
investigator in his pursuit of the cause of a patient's anemia. By obtaining a complete blood
count (CBC) on a patient in whom anemia is suspected, the physician can categorize the anemia
into its appropriate morphologic type. Thus, insight is provided into subsequent diagnostic
studies necessary to determine the precise mechanism involved. The importance of disclosing
the etiology of the anemia cannot be overstated; "anemia" in and of itself is not a specific
diagnosis. Administration of blood, iron, or multivitamins on the basis of "anemia" without a
specific diagnosis may jeopardize a patient's chances for ultimate recovery.
Volume Packed Red Cells
(cc/1000 CO blood)
RBC (millions/cu mm)
= Hemoglobin (gm/1000 cc blood)
RBC (miUions/cu mm)
Hemo^obin (gm/100 cc blood)
Volume Packed RBC
(cc/100 cc blood)
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U.S. Naval Pli^t Surgeon's Manual
Table 5-12
Morphologic Classification of Anemias
Anemia Classification
Criteria
Disease Type
■Macrocytic
With "Megaloblastic" iWarrow
MCV > 94 cju
IVICHC>35%
Macrocytosis, Anisocytosis,
Poikilocytosis (Teardrop)
on Smear
Pernicious Anemia Type
Without "IVIegatoblastic"
iviarrow
IVlCV>94cpi
IvtCHC > 30%
Macrocytosis, Target Cells
on Smear
Liver Disease
(VHcrocytic
MCV<94ciU
MCHC>30%, it sutrclassified
as simple
MCHC<30%, if subclassified
ws "Hypochromic"
Microcytosis, Hypochromia,
Anisocytosis, Poikilocytosis
on Smear
Nutritional Anemias
Repeated Pregnancy
Prematurity
Inadequate Iron Intake
in Infants (Milk
Anemias)
Chronic Blood Loss
Thalassemia
Deficiency
Normocytic
MCV 80 to 94 CJU
MCHC > 30%
Normocytosis, Normochromia,
Slight Anisocytosis and
Poikilocytosis on Smear
Recent Bleeding
Hemolysis
Marrow Replacement
Marrow Depression
In general, uncorrected anemia is cause for grounding of an aviator. If the etiology of the
anemia is found and corrective measures are taken, the aviator can be returned to an "up" status
as long as control of the aiiemia can be maintained. Obviously, some causes of anemia are
beyond treatment, in which case the aviator would be permanently grounded.
Hemo^obinopathies
Again, this topic is quite lengthy; discussion herein wiU be primarily hmitcd to sickle cell
disease and thalassemia. Sickle cell hemoglobin (HGB S) represents a qualitative hemoglobin
abnormaUty, while thalassemia represents a quantitative disorder of hemoglobin.
HGB S aggregates when deoxygenated, thus distorting red cells and impairing microcircula-
tion. Clumps of siclded ceUs occluding circulation result in local pain, necrosis, and fibrosis;
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Internal Medicine
often, symptoms of "crisis" are bizarre and involve many areas of the body simultaneously. In
addition lo hemolvtic anemia and vascular occlusion, patients with sickle ceU anemia may have
severe iirfections. Although sickle ceU trait is usuaUy unassociated With manifestations of
disease, hematuria may be present. According to LeaveU and Thorup (1971), patients with
sicMe cell trait have reportedly developed splenic infarction while flying at high altitude; others
have died while involved in strenuous physical exercise (Jones, Binder, & Donowho, 1970).
Currently, sicHe cell disease (either anemia or trait) is considered disqualifying for duty as a
naval aviator or naval flight officer.
Thalassemia, as used here, refers to Ag thalassemia (a variety of ^-thalassemia) in which the
A2 hemoglobm fraction is elevated. Fetal hemoglobin (HGB F) levels axe slightly elevated, and
microcytosis with target cells can be seen on smear. Examination may demonstrate moderate
splenomegaly. There are three clinical subdivisions of thalassemia (1) thalassemia minor,
(2) thalassemia intermedia, and (3) thalassemia major. Thalassemia minor is often discovered by
accident in an asymptomatic patient. This "sttent*' form (sometimes described as thalassemia
minor, variant miiiittia) is compatible with a normal Ufe-span during which there are no chnieal
manifestations of the disorder. This diagnosis, if confirmed by the hemoglobin electrophoretic
pattern in an asymptomatic patient, is not disqualifying for aviation.
In thalassemia intermedia, there is mild to marked splenomegaly, jaundice, recurrent
abdominal pain (as a result of cholehthiasis or splenic enlargement), and skeletal changes simflar
to those in thalassemia major. Both thalassemia intermedia and thalassemia major are
disqualifying.
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U.S. Naval Hi^t Surgeon's Manual
SECTION IV: INFECTIOUS DISEASE
Infectious disease in the aviation community is generally limited to the acute contagious
infeetions hecawse of the young age group, requirement for excellent physical condition,
ag^essiye preventive medicine program, and the semiclosed population. These infections include
the more common viral diseases, venereal diseases, tuberculosis, Neisseria meningitis, and
protoza. Two handbook references that are continuously current are the Handbook of
Antimicrobial Therapy and the Guide to Antimicrobial Therapy. The infectious disease section
in Harrison's Principles of Internal Medicine is an excellent textbook reference. In general, the
ri^d demands of the aviator require that he be grounded while symptomatic and for 24 hours
after completion of medical therapy.
Viral Disease
Viral disease in the aviation community is a major cause of "down" time. This category
includes upper respiratory infection, influenza, infectious mononucleosis, and hepatitis.
Treatment is symptomatic with observation for complication. With an infection of viral
etiology, prophylactic antibiotic therapy should be withheld because of the risk of secondary
infection with a resistant organism, toxicity of drugs, expense, and confusion with improperly
treated bacterial infections (Wintrobe, Thorn, Adams, Braunwald, Isselbacher, & Petersdorf,
1974). Antibiotic prescription in these situations is a poor substitute for frequent chnical
observation and appropriate cultures. If bacterial etiology is suspected, cultures should be taken
and antibiotic therapy begun. This should be terminated in five days if clinical or culture results
are negative.
Upper Re8{iiratory Infection
Rhinorrhea, pharyngitis, and sinus congestion compromise the patency of the Eustachian
tube and, in the aviation environment, predispose to middle ear disorders such as vertigo and/or
bacterial infection. Treatment is symptomatic with rest, increased fluids, and antihistamine
therapy. The aviator is grounded until he has been off medication for 24 hours and proof of
normal tympanic membrane motion is obtained. In recurrent ilhiess, an allergic process should
be sought. Secondary complications including otitis media, sinusitis, and/or bronchitis increase
"down" time.
Influenza
The miUtary community is considered a high risk group for influeMa. There are three types
of influenza virus, lal>rled A, B, and C (Wintrobe et al., 1974). Influenza C causes mfld upper
respiratory infection symptoms. Influenza B causes mild flu symptoms. Influenza A causes the
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Internal Medicine
major epidemic at two to four year intervals, and its antigenic changes result in morbidity and
mortality as recorded in the epidemics of 1918 ^ Swine flu, 1957 ^ Asian flu, and
1968 - Hong Kong flu. BuMed recommendations for vaccination are reviewed yearly to reflect
the situation actually present for that year. The vaccination program should be scheduled S®
that the entire unit is not incapacitated at the same time. The aviator is down for at least eight
hours and preferably for 24 hours post-vaccination with observation for acute anaphylactic
reaction and influenza syndrome.
The incubation period is less than three days, and the acute symptoms last an average of
three days. During an acute episode, the aviator is in a "down" status and tieated
symptomaticaUy with rest, analgesics, increased fluids, and observations for secondary
compUcations, mainly bacterial pneumonia. Prophylactic antibiotic and amantadine therapy we
not recommended. In an unusual epidemic sitiiation, the infectious disease department of the
regional medical center or the Communicable Disease Center should be contacted for guideUnes
on the need for typing of virus and the vaccination programs.
A special awareness is required to assess tiie impact of influenza on the readiness of tiie
aircrewmen to resume flying duties in tiie presence of the ill-defined, but important,
postinfluenza syndrome characteriaed by noiispecific fatigabiUty and vague lassitude. In such an
instance, where physical examination and laboratory values are normal, return to flight statiis
should be delayed pending resolution of the symptom complex.
Infectious Mononucleosis
The clinical syndrome of fever, pharyngitis, lymp adenopathy, and lymphocytosis with many
atypical lymphocytes in the young adult suggests mononucleosis caused by the Epstem-Barr
virus It warrants a mononudeo* heterophil test, and, if negative, the test should be repeated
in two weeks for confirmation. The acute illness lasts from two to four weeks with gradual
return to full capacity. Treatment is symptomatic with rest, analgesics, and observation for
comphcations which include airway obstruction, aseptic meningitis, encephalitis, Guillain-Barre
syndrome, hemolytic anemia, thrombocytopenia purpura, myocarditis, pericarditis, and splemc
rupture (Wintrobe etal., 1974). Prednisone 40 to 60 mg q.d. is recommended for treatment of
these severe comphcations.
The aviator is in a "down" status until he is returned to normal activity following
convalescence. A medical board and/or convalescent leave may be necessary in protracted cases.
The persistent presence of a peripheral right shift or splenomegaly as the only dise^e residttal m
clearly recuperating patients constitutf^s objective evidence that the patient is not yet ready for
aviation duties.
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U.S. Naval Fli^t Surgeon's Manual
Hepatitis
The symptom complex of anorexia, fatigue, malaise, loss of taste for cigartttes, and weight
loss, evolving in a period of 2 to 14 days to dark urine, jaundice, and right upper quadrant
tenderness is classical in the young adult with hepatitis. The liver function tests reveal decreased
prothrombin time, etevated SCOT and SGPT, normal to minimally elevated alkaline
phosphatase, and elevated bilirubin. Full cEnical and biochemieal recovery usually takes three to
four months (Wintrobe et al., 1974). Treatment is symptomatic with rest (absolute rest for one
hour after meals), high caloric diet, and abstinence from alcohol. Hospitalization is required for
clinicaUy severe illness, posttransfusion hepatitis (10 to 12 percent mortality), and if diagnostic
liver biopsy is needed. Steroid therapy is contraindicated in acute viral hepatitis (Gregory,
Kn^er, Kempson, & Miller, 1976). Aviators are grounded until Hver function tests return to
normal. A medical board and/or convalescent leave is usually necessary.
There are two known viruses that cause hepatitis, designated A and B. Both have been
proven to be spread by oral and parenteral routes. Therefore, proper hygiene should be
practiced, such as washing hands after patient examination and proper handling of blood, urine,
feees, and saUVa. Hepatitis A Is a disease of young adults with an incubation period of 15 to
SO days. Transmission is primarily person to person by the feeal^oral route, but also from
eoiitjBKinated foods and transfuaion. A specific laboratory assay for the antibody to hepatitis A
may be available to selected medical communities (Dienstag, Routenberg, Pareell, Hooper, &
Harrison, 1975; Szmuness, Dienstag, PurceU, Harky, Stevens, & Wong, 1976). Intimate contacts
of patients with hepatitis A should receive immune serum globulin 0.01 ml per pound of body
weight I.M. as soon after the exposure as possible (Wintrobe et al., 1974).
Itepatitis B has no age preponderance with m incubation period of 50 to 180 days. It is
primarily transmitted parenterally but also by sahva (Villarejos, Visona, Gutierrez, & Rodriguez,
1974) and possibly by intercourse. Effectiveness of hepatitis B hyperimmune globuUn i^
problematic but has been demonstrated to be effective in certain situations (Gitnick, Goldberg
Koretz, & Walsh, 1976).
The Flight Surgeon has an obligation to define as clearly as possible the epidemiologic
impUcations of each case.
Tuberculcffiis
Extensive instructions for testing, treatment, and disposition of tuberculosis (TB) cases are
contained in NAVMED P.5052-20 and BUMEDINST 6224.1D. Ail cases of active TB are to be
expeditiously transferred to a tuberculosis treatment center. These are NRMC, Portsmouth, Va.,
and NRMC, San Diego, Ca. A Disease Alert Report, MED-6220-3, is submitted. Current
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bitental MetCcine
treatment protocd kcludes education of the patient to control cou^ ih brdfer tcJ ptevmt
spread of the disease, as infectiousness is present until 10 to 14 days after starting an adequate
treatm^t program. A chemotherapy program of two or three drugs is recommended. These
drugs include isoniazid (INH) plus ethambutol or rifampin as the second drug and streptomycin
as the third drug, depending on the sensitivity of the organsim and patient tolerance. After
demonstration that the chemotherapy program is effective, the patient is boarded to limited
duty for ^e'teation (18 to 24 months) of chemotherapy. Current treatment programs are
under investigation with indications that duration of therapy may be reduced to 6 to
II months with acceptable relapse rates of two to three percent (Second East African, 1976;
Johnston & Wildrick, 1974). Steroid therapy is indicated in life threatening situations only
(Wintrobe et al., 1974).
The aviator is grounded for the duration of chemotherapy and then returned to active
flying status if there are no residual physical disqualifying defects.
Preventative therapy of TB is based on the facts that transmission of TB is by aerosolized
droplets and that the natural history of TB includes the reactivation of dormant disease. With
discovery of an active case of TB, a contact investigation is begun. This ineludes aU who share
the same berthing faciKtiea, those in close contact during duty hours, r^iflar Hberty |n||tes^
dependents of patients. This is extended on ships to include the entire ship's company, if less
than 350. onboard personnel, or crewmembers served by the same ventilation system, and in
commands with exceptionaUy close conditions. Decontamination of affected spaces involves
changing of filters in ventilation systems and cleaning of the patient's berthing spaces and
bedding.
The screening examination for close contacts includes tuberculin skin test using five units of
•purified protein derivative of tubercuHn intradermally (IPPD) and chest X-ray with results
recorded on NAVMED 6224/1 in the Health Record. Re-examination is done at three, six, and
twelve months. Previous tubercuUn reactors are screened with chest X-ray only. If no active
disease is present, but the IPPD is greater lhan 5 mm, INH 300 mg q.d. is given for one year
unless contraindications exist. If the screening test is negative, INH prophylms may begin based
on the cUnical situation, to he discontinued at three months if re-examination contmues
negative (American Thoracic Society, 1974). Children should begin on INH, 10 to 15 mg/kg not
to exceed 300 mg, even if the initial IPPD is negative. If the IPPD continues to be negative at
three months, then therapy may be stopped. If the IPPD becomes positive, then a 12-month
course of chemoprophylaxis is begun.
INH preventive therapy is a balance between the percent of reactivation of disease over a
period of time and the risk of side effect, namely INH hepatitis. Current recommendations
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U.S. Naval Fli^t Surgeon^ Manual
(American Thoracic Society, 1974; BUMED 6224.ID, 1975) are to begin 12-month INH
prophylaxis in the foUpwipg cases;
1. IPPD converter in the past two years
2. Positive IPPD with chest X-ray consistent With iriaclive fB, m& negative APB smear
and culture, and without prior adequate chemotherapy
3. Positive IPPD with diabetes melHtus, hematolo^cal or reticuloendothelial disease,
prolonged steroid therapy, immunosuppressive therapy, alicosis, and postgastrectomy
4. Manditory for IPPD-positive children under six years and highly recommended to age
35 years, unless specific contraindications exist.
Specific contraindications to INH therapy include previous INH hepatic injury, adverse
reaction to INH such as drug fever, chills, rash, and arthritis, acute liver disease of any etiology,
and pregnancy. Special attention should be paid to people on long-term medications such as
diphenylhydantoin, daily users of alcohol, patients with chronic Uver disease, and those with a
history of prior discontinuance of INH secondary to a questionable reaction.
The aviator is returned to flight status while receiving INH prophylaxis once the FHght
Surgeon has established that no untoward reactions are ongoing. This may require an initial
two-week grounding with biiveekly clinical observation.
Individuals on INH chemoprophylaxia should be educated to the toxic symptoms and
queried monthly about adverse signs and symptoms of hepatitis. Should they occur, tiie patient
is instructed to immediately discontinue INH therapy and report for evaluation of liver disease.
Routine Uver function tests are not recommended. An isolated SGOT elevation less than
100 l.U. is not sufficient reason for stopping therapy.
Malaria
Malaria is transmitted by the bite of the Anopheles mosquito and should be suspected in
any ill person returning from m endemic area. The symptoms of chills, fever, headache, muscle
pains, associated splenomegaly, and anemia should occur within three weeks of exposure.
The first attacks are severe, but repeated attacks become milder. The diagnosis is confirmed
by finding parasitized erythrocytes on Wright's or Giemsa-stained smears. The parasites should
be seen and diagnosed on at least one slide, if blood is obtained every six hours during a
twenty-four hour period. Associated laboratory findings are a normal or low white count and an
elevated erythrocyte sedimentation rate.
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Internal Medicine
Complications associated with malaria are spontaneous rupture of the spleen, bacillarjr
dysentery, cholera, and pyogenic pneumonia. The treatment of acute attack consists of
chloroquine, 0.6 gms (four tablets) initially, 0.3 gms (two tablets) six houts later, 0.3 gms
(two tablets) daily times two, and pyrimethamine, 25 mg b.i.d. times three days. If a patient is
suspected of having drug resistant P. falcipamm, a eomhination of quinine, pyrimethamine, and
sulfonamide or sulfones should be given for ten days. To clear the liver of parasites as in
P. vivax, P. ovale, or P. malariae, a 14-day course of 15 mg primaquine base p.o. will effect cure
in most cases. Primaquine may cause hemolysis in persons with G-6-PD deficiency. Prophylaxis
for adults residing in an endemic area is chloroquine base, 300 mg per week, and primaquine,
30 mg per week. Aviators with acute malaria under treatment are grounded. On the prophylaxis
above, they are permitted to fly.
Minor protozoan diseases usually are found incidentally in evaluation of eosinophiUa or
malabsorption. The ova and parasites are seen most often when fresh stool specimens are
examined. The most common are those of giardiasis, hookworm, strongyloidiases, ascariasis, and
enterobiasis (pinworra). Current ' recommended therapy is chai^g r^idly as new
anti-helminths become available; therefore, a current text on tropical or internal medicine
should be consulted with regard to the drug of choice.
AmebiaBis
The ntiEgor protozoan disea^S with world wide distribution are amebiasis and malaria. Both
diseases are more common in underdeveloped tropical and subtropical countries, but they are
also seen in military personnel and civilians returning from these areas.
Amebiasis is caused by EnUimoeha histolytica. It fe the only one of the seven different
species which parasitize the mouth and intestine of man, which causes disease. There awi two
forms of Entamoeba histolpica, the motile trophozoite and the cyst. The trophozoites are
passed in tiie stool undianged when diarrhea is present. If there is no diarrhea, the trophozoites
wiU encyst before passage in the stool. It is the cyst which causes disease, and the usual route is
through fecal contamination of food or water.
The clinical manifestations are the asymptomatic cyst passer and the symptomatic,
intestinal amebiasis presenting with intermittent diarrhea progressing to the fulminant attack of
amebic dysentery with high fever, severe abdominal cramps, and profuse bloody diarrhea with
tenesmus. In these patients, trophozoites are numerous in stools and on the material obtained
from ulcers in the cecum and rectum. Hepatic amebiasis occurs as a result of the parasite
invading the hver via the portal vein. This may be followed by the development of a single
hepatic abscess in the posterior portion of the right lobe of the hver. Clinical findings of the
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U.S. Naval Fli^t Surgeon's Manual
discess are fever, night sweats, weight loss, and sometimes tender hepatomegaly. Occasionally,
an abscess will extend into the right pleural cavity and lung. These people will present with
cough, pleural pain, fever, and leufcoeyto^s as a rule; a secondary bacterial infection is frequent.
The diagnosis is made by finding the cyst in formed stools or the trophozoite in liquid stool.
Treatment of intestinal amebiasis is metromidazole (Flagyl) 800 mg t.i.d, times 5 days. If
hepatic abscess is suspected, chloroquine is the drug of choice. It is nontoxic, effective, and
produces symptomatic relief in 48 to 72 hours. While on treatment for any form of amebiasis,
the aviator is grounded.
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biternd Medicine
SECTION V: METABOUC DISORDERS
Adrenal Disorders
A brief summary of adrenal disorders is as follows:
1. Glucocorticoid Excess
a. Cushing's Disease (Pituitary ACTH excess)
b. Cushing's Syndrome (either adrenal neoplasia or ectopic ACTH production)
2. Glucocorticoid Insufficiency
a. Primary Adrenocortical Failure (Addison's)
b. Secondary Adrenocortical Failure
c. Adrenogenital Syndromes (rare and extremely unlikely to be disclosed in aviation
personnel).
The Flight Surgeon is referred to standard medical texts for complete discussions of these
dysfunctions. Either state is a grounding defect and warrants follow-up within the hospital
system. Return to aviation following treatment 18 most unlikely.
< Thyroid DiBorders
Hyperthyroidism
Simply defined, hyperthyroidism is excessive production of thyroid hormones resulting in a
hypermetabohc state with associated adrenei^c-like symptoms.
Hyperthyroidism may be subdividted into relatively common and relatively rare forms. The
most common forms include Graves' disease, toxic multinodular goiter, toxic adenoma, and
factitious hyperthyroidism. Relatively rare forms include choriocarcinoma, metastatic testicular
embryonal cell carcinoma, and struma. Treatment of hyperthyroidism includes medcal agents
and surgical approaches. Medical management may take the form of
1. iodine (for emergency treatment of thyroid storm or in preoperative patients) to reduce
thyroid vascularity
2. Propylthiouracil (PTU)/methiraazole (Tapazole)
3. resetfane and guanethidine
4. propranolol
5. radioactive iodine (treatment of clioice in patients over 40 years of age).
Surgical treatment is utilized in patients who should not have radioiodine or in whom
intolerance to other modes of medical therapy is experienced.
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U.S. Naval Fli^t Sutgeon'a Manual
It is of importance to point oJlt-t^t hyperthyroidism is disqualifying in the aviator unless
definitive treatment (either jl^l qj surgical thyroidectomy) has been undertaken. In either of
these instances, the potential for subsequent hypothyroidism is present.
Hypothyroidism
Hypothyroidism i^ a atate of thyroid insufficiency in which a hypometabolic condition
opposite that of hyperthyroidisitt ensues*
The most common form of hypothyroidism is that of primary hypothyroidism in which the
thyroid gland itself cannot synthesize sufficient thyroid hormone for metabolic needs, The
second most common form of hypothyroidism is observed following therapy. Radioactive I^^l
therapy results in 25 percent of patients being hypothyroid at the end of one year and
50 percent of patients being hypothyroid at the end of 10 years. Other causes of
hypothyroidism are uncommon, but virtually all require thyroid replacement (i.e., unless
over-suppression by medical therapy for hyperthyroidism is the etiology).
If replacement therapy results in a euthyroid state, the aviator may be considered for a
return to flight status, as long as follow-up thyroid studies and replacement therapy can be
made available. Isolated duty assignments for the treated hypothyroid aviator must be avoided;
this may necessitate removal from Service Group I and appearance before a Local or Special
Board of Flight Surgeons (LBFS or SBFS) in order to determine final disposition.
Disorders of Gfaicose Metabolism
Diabetes Mellitus
Diabates mellitus is a funcHonai disttfrhttncp of paaci^atLfi islet cells resulting in metaboUc
abnormalities in the handling of not only sugars, but proteins and fats, as well. It constitutes the
fifth leading cause of death in the United States behind cqronary artery disease, cancer,
accidents, and renal disease. Over 50 percent of diabetics die because of coronary artery disease;
diabetes is also the leading cause of adult blindness.
Diabetes mellitus has been classified ki four stages:
1. Prediabetic Stage — This stage can be suspected on the basis of family history, but is
never diagnosed clinically.
2. Subclinical Stage — There is a normal fasting blood sugar, but an abnormal glucose
tokrance test (GTT) under conditions of stress.
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Internal Medicine
3. Latent (Chemical) Diabetes — There is a normal fasting blood sugar, but an abnormal
GTT in the absence of stress.
4. Overt Diabetes — The fasting blood sugar is clearly elevated. A glucose tolerance test
carries a risk to the patient and is not essential to the diagnosis. Even the early overt
diabetic may have a fluctuating cpijiree, in that a remission, "Honeymoon Phase," may
return the patient to a latent o% subclinical stage prior to the reappearance of overt
diabetes in 1 to 18 months.
Common presenting signs or symptoms include the following:
1. Fatigability (75%)
2. Nocturia (74%)
3. Polyuria (74%)
4. Polydypsia (66%)
5. Weight Loss (59%)
6. Routine GTT (53%).
Some five percent of overt diabetics initially present in diabetic ketoacidosis.
Laboratory diagnosis is a controversial issue, especially in terms of interpretation of the
gUicose tolerance test. Conditions under which a GTT should be done must be rigorous;
1. The patient must be on a carbohydrate-loading diet (300 gms/day) for a iMiJttiittarn of
three days.
2. The patient must be rested, relaxed, and fully ambulatory.
3. The test roust be done in the morning.
4. The patient must be free from acute iUness.
5. The patient should not be taking medication nor should he smoke during the test.
The physician must, himself, be acquainted vrith the laboratory techniques since plasma values
are 15 to 20 percent higher than whole blood values.
Two commonly used criteria for interpretation of GTT's are outlined in Table 5-13.
Fajans-Corm criteria require that all three values (1, VA, and 2 hours) be exceeded for the
diagnosis. For a positive dia^osis under the U.S.P.H.S. point system, two points are required.
Bear in mind that an abnormal GTT (i.e., one which does not meet the above diagnostic
criteria) is not the equivalent of diabetes. The oral GTT is a poorly reproducible study and, for
that reason alone, must be viewed with caution. To improperly label a patient as diabetic is as
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U.S. Naval Flight Surgeon's Manual
grave an injustice to him as is missing the diagnosis in a patient who is clearly diabetic on clinical
and laboratoiy groimde. For these Mibdinical or latent diafaetics ("glucose intolerance" being a
better ciipiee of tenns in most instances), wei^l control and dietary progcams are likely
indicated.
Table 5-13
Interpretation of Values for the Standard GTT
Fajans-Conn
U,S. Public Health Service
Whole Blood
{mg %)
Plasma
(mg%)
Whole Blood
(mg%)
Plasma
(mg%)
Poifits
Fasting
1 hour
1 Vs hours
2 hours
3 hours
As a matter
160
140
120
of point, there
185
150
140
- is no place in
110
170
120
110
naval aviation
130
195
140
125
for the overt
1
'^
%
1
diabetic, insulin
dependent or not Oral hypoglycemics should not be considered as a means of keeping the pilot
"up" since undesired side effecfe, e.g., hypoglycemia, may bring catastrophic results.
Hypoglycemia
Hypoglycemia indicates excessively rapid removal of glucose from the blood or an inabihty
of gluconeogenesis to sustain adequate glucose levels. ^
When blood sugar falls at a precipitous rate, the patient displays signs of hyper-
epmephrinemia, e.g., nervousness, palpitations, sweating, pallor, hunger, headache, and
tremulowsness. A slower fall in glucose (w^ch may, result in a lower blood Sugar tjfiaii l^f former
state) may give rise to cerebral symptoms, e.g., blunred vision, somnolence, syncope, coma, and
even seizures.
Hypoglycemia, which is not a specific disease state iii and of itself, is classified as being
either Ainctional or organic. Organic hypoglycemia is related to a known anatomic lesion.
Examples include beta-cell tumor of the pancreas, adrenocortical hypofunction, anterior
pituitary hypofunction, epithelioid tumors derived from neural crest (e.g., insulin -producing
carcinoid tumor). Functional hypoglycemia has no specific anatomic lesion. Examples include
1. exogenous hypoglycemia
a. iatrogenic — the diabetic who takes too much insulin
b. factitious — abuse by patients who have access to hypoglycemia drugs
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Internal Medicine
2. reactive hypoglycemia
a. alimentary hypoglycemia in postoperative gastrectomy or gastrojejunostomy
patients
b. as a manifestation of glucose intolerance in the subclinical or latent diabetic
c. "functional" hypoglycemia in the tense, anxious patient
3. hepatic dysfunction resulting in decreased gluconeogenesis. Most commonly, this is seen
in the alcohol abuser who drinks excessively after periods of relative malnutrition or
starvation.
In aviation personnel with a history suggestive of hypoglycemia, extensive evaluation may
be required to document the abnormahty and, whenever possible, the underlying cause. Caution
should be observed in performing studies mch m t2-liour fast or tolbutamide tolerance test;
these should be reserved for the hoqjjtaMzed patient under careful observation. As ^ated
previously, the interpretation of oral GTTs is an area fraught with pitfalls. Tltie asymptomatijil
patient whose blood sugar at three hours falls to 50 mg% from a two'bour level of 90 mg% is
more likely to be a variant of normal than is the patient who develops symptoms at three hours
with a blood sugar of 65 mg%, having fallen from a two-hour value of 165 mg%.
If disclosed, any underlying anatomic disorder in a patient demonstrating hypoglycemia
should be treated. In those who have no evident etiology, dietary msmagement (to include
high-protein, six-feeding diet) should be employed. Appropriate control of hypoglycemic
episodes must be attained prior to the patient's return to an "up" status; such control may take
six months or more to achieve. In those aviators with continued episodes while under optimal
dietary management, permanent grounding may be in order.
Hyperlipidemias
Classification
Hyperlipoproteinemias may be classified into five groups on the basis of plasma appearance
and electrophoretic pattern, serum cholesterol, and triglyceride concentration.
Type I. Type I is cbaracterized by increased dhylomierons in the blood serum which
produce a milky fasting serum. If the specimen is allowed to stand at 4" C overnight,
lactescence will rise like cream, leaving a transparent infranate. Triglyceride levels of 1,000 to
10, 000 mg% are seen. Ultralow density particles derived from the diet via lymphatics,
i.e., chylomicrons, form a dense band on electrophoresis. The underlying abnormality appears
to be a genetic defect (recessive trait) which insults in a lipoprotein hpase deficiency. The
disease may appear in early childhood and presents as abdominal pain, distention, and an
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U.S. Naval Flight Surgeon's Manual
increase of pancreatic enaymes. Xanthomas, hepatosplenomegaly, and lipemia retinalis may
be present.
Type IL Type n accounts for a szeable number of individuals who are identified by an
elevation of serum chole.sf erol. Familial Type n is an autosomal dominant trait, and evidence is
strong for the presence of accelerated vascular disease. In the homozygous state, coronary artery
disease may express itself in childhood. Tendinous xanthomas of the Achilles tendon or other
extensor tendons may occur. Tuberous xanthomas over the elbows, knees, buttocks, and hands
are common. Xanthelasmas may be present, along with arcus comealis. Cholesterol is elevated,
and the plasma is clear (Type IIA) to very sH^tly turbid (Type IIB). Electrophoresis shows a
broad jS-band (with a pre-p band in many Type HB's).
Type III. Type III is probably an autosomal recessive trait. It is less common than Types II
and IV. Both triglycerides and cholesterol are moderately elevated, and serum allowed to stand
overnight at 4° C takes on a moderately turbid appearance. A dense, broad (3-band (generally
fused with a pre-^ band) is present on electrophoresis. Xanthomas, xanthelasmas, and corneal
arcus may be present.
Type IV. Type IV is probably the most common hpid disturbance in the adult American
population. It is clearly exacerbated by obesity and alcohol; two-thirds of the patients have
^ueose intolerance. Cholesterol is normal to slightly elevated: triglyceride levels range from
200 to 2000 mg%. A dense pte-(3 band is present on electrophoresis; serum takes on a turbid
appearance overnight at 4° C. Fasting plasma lactescence may be present, indicative of "hepatic
particles" (triglycerides synthesized in the liver). Xanthomas, corneal arcus, and premature
vascular disease may develop, depending upon lipid levels, at least in part.
Type V. Type V patients have both elevated cholesterol and triglycerides. The triglycerides,
themselve?, are an admixture of chylomicrons and hepatic particle triglyeerideg. Obesity,
abdominal pain, pancreatitis, lipemia retinalis, and xanthomas are common. The trait is likely
recessive. Dense chylomicron, jS-, and pre-|3-bands are seen on electrophoresis; plasma after
overnight refrigeration separates into a cream-layer supernatant and a milky infranatant.
Treatment
Non-medical treatment for the five types of hyperlipidemia is outUned below:
'type I — Low-fat diet (less than 30 gms daily), medium chain triglycerides (25 percent
of calories)
Type II — Dietary restriction of cholesterol with substitution of polyunsaturated fats
for saturated fats. Weight loss is important for those Type 11 patients with
obesity.
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Internal Medicine
Type ni - Reduction to an ideal body weight with limitation of carbohydrates and
alcohol
Type lY - Weight reduction with restriction of alcohol and carbohydrates
Type V - Control of simple sugar and alcohol intake. Weight control is of the essence
since obesity in Type V patients is the rule, rather than the exception.
It can be seen from the outline that weight reduction is the cornerstone to management of most
patients with hyperlipidemias.
Drugs currently utilized in the management of lipid disorders include clofibrate,
cholestyramine, colestipal, neomycin, sitosterol, nicotinic acid, and d-thyroxine.
Clofibrate is of primary use in carbohydrate-induced hyperlipemia, but it is not of value in
primary hypercholesterolemia. It works by decreasing the synthesis of hepatic particles and
increasing their catabolism. It potentiates warfarin and may adversely affect blood coagulation.
Cholestyramine interrupts enterohepatic circulation of bile acids and cholesterol. This
action speeds the conversion of cholesterol to bile acid and, thereby, lowers serum cholesterol.
Colestipal, neomycin, and sitosterol function in a manner analogous to cholestyramine.
Nicotinic acid inhibits adipose tissue lipolysis and decreases hver synthesis of hepatic
piirticles and cholesterol. It is particularly effective in hypercholesterolemia in concert with
cholestyramine.
d-Thyroxine is designed to have the hypocholesterolcmic effects, without the metabolic
effects, of native thyroid hormone.
Disposition of aviators with lipid disturbances is most dependent upon their response to diet
and weight control. Failure to respond to the non-medical regimen may require medication
which will ground the patient until (1) hpid levels normalize and the medication is discontinued,
or (2) sufficient time has passed to assess potential side effects. In the latter event, should the
patient be free from adverse reactions to the drug(s), a return to flight status, after a
three-month observation period while on medication, might be considered. Most patients,
however, do not require medication and can be treated by weight control and diet with process
monitored simply by a scale and repeat lipid studies.
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U.S. Naval Flight Surgeon's Manual
Obesity
Almost all cases of obesity are due to exogenous factors, speGifically ealoric intake in excess
of caloric expenditure. Other causes are not worthy of review; neither will space be taken to
reproduce weight standards for aviation.
For ease of calculation, one can utilize the figure of 3500 calories as equivalent to one
pound of body fat. Multiplication of 3500 by the number of pounds in excess of standards (or
desired wei^t) results in calculation of total number of calories in excess. For example, a
73-mch male weighs 219 pounds, which is ten pounds over maxilnum aviation weight standards
for height; 3500 cal./lb. x 10 lbs. = 35,000 calories in excess. To calculate rate of loss,
maintenance caloric intake is first figured by multiplying present weight 219 lbs. x 10 (cal./lb.).
Therefore, 2190 cal./day are required in order to maintain wei^t. Maintenance caloric intake
minus specified caloric-restricted diet provides the daily caloric deficit. In this instance, an
1800 calorie diet is ordered, giving a daily caloric deficit of 390 calories (2190 — 1800). The
deficit is divided into the total caloric excess, thereby calculating the number of days required
to lose the excess weight, i.e. 35,000 cai./390 cal./day = approximately 90 days. The desired
weight can be maintained, thereafter, by 2090 cal./day (209 lbs. x 10 cal./lb.)
Wright and Wilmore (1974) published methods of estimating relative body fat and lean body
weight. The following equations were used:
Lean Body Weight (kg) = 40.99 + 1.0435 x Weight (kg) ~
0.6734 X Abdominal Circumference (cm) (at umbilicus level)
Fat Weight = Weight - Lean Body Weight
Relative Fat - (Fat Weight/Weight) x 100.
Reported range of relative fat in healthy young males was from 12.5 to 18.7 percent, while the
mean value for Marine Corps personnel under study was 16.5 percent.
In essence, obesity is almost uniformly exogenous in etiology; most other causes are readily
diagnosed by physical examination and/or through historical information. Weight loss requires
insight and determination on the part of the patient, but it also requires concern and support
(including referral of patient and spouse to the dietitian) on the part of the physician. The
results of patient effort and participation are easily seen and can be monitored by a simple
device — the scale. Obese patients should be grounded until the desired weight is attained;
follow-up to observe continued maintenance of desired weight is necessary and should include
grounding if interval weight gain is present.
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internal Medicine
Hyperurii!^inia
In all patients found to have elevated serum uric acid values greater than 8 mg%, a search
should be made to find underlying hematologic disorders, chronic renal diseases, or hypertensive
cardiovascular disease. When these have been excluded, therapy should be started to achieve a
serum uric add JeviA M®^ tinflt^.V&e *M«*t aiifl simplest approacM ft ttt dietary
purine ii^fflMci. Hyiraitf&iJ Ae|(ktiihf t©"5obrt*?Et^firtM»%^ day is
helpful. Secondly, aLkahnization of the urine preventBf']^fecipitation of the uric acid crystals in
the kidney. This can be accomplished by 250 mg acetazolamide (Diamox) daily. Thirdly,
allopurinol may be given in dosages of 100 mg, two to four times daily. This blocks formation
of uric acid from xanthine and hypoxanthine. Aviators being treated with these medications are
in an "up" status if adverse side-effects are not experienced in a three-month trial of therapy.
t
I
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U.S. Naval Flight Sur^on'B Manual
SECTION VI: PULMOlSfARY DISEASE
Aihiioiuiry Function Testing
Although a great deal can be learned about the lungs from the history, physical
<e^|i|p4fta^W, i^d chest X-ray, fuhnomuy ftinction testing ean biK a usi^ful adjunct to describe
£i#(3<,^pl^ti|y inany properties of the respiratory system. Several of the more important and
simple tests will be 4isW!^4 her© md s^pplicabiUty , t» ayi^iliij]^; ,lil^icin@ sitiifttiojas wU. te
rioted. 1 ; . ,
Volume-Time Spirometry
Volume-time spirometry measures the traditional forced vital capacity maneuver {Fig-
ure 5-SO). A diminution of the vital ci^aeity represents significant restrictive diseases of the
lung (e.g., collapse, infiltrates, chest wall deformities, or neuromuscular dysfunction). The
amount of air expired in the first second of this forced maneuver (FEV^) is the classical, but
insensitive, indicator of airway obstruction (e.g., significant bronchitis, acute asthma). These
tests may be useful in following the recovery from reversible lung disorders in pilots, but their
insensitiviiy makes their use as a screening tool unwarranted.
o
>
Forced
Vital
Capacity
IVC)
1 Sec.
Time
Figure 5-30. Graph of forced volume-time spiiometry.
5-78
Interna! Medicine
Flow-Volume Spirometry
Thig test (Figure 5-31) uses the same forced vital capacity maneuver as volume-time
spirometry, but here the flow rates are measured and plotted against the percentage of vital
capacity expired. This is useful for measurinjg the mid- and end-^piratiEiig^ OipJS ptoj i«0
difficult to determine from the volume-time (surve. It is these flow; KlrtmiiftMit a#44t!jc» hts
sensitive indicators of airway dysfunction in otherwise asymptomatic individuals. Presumably,
abnormalities here reflect a predisposition to subsequent obstructive pulmonary disease. Thus,
thcbt measurements are potentially useful screening tools to identify high risk groups in an
effort to alter their pulmonary stress factors (e.g., smoking, environment). Newer techniques
comparing, flows at room air versus flows using helium may enhance their effectiveness.
Tm 50% 75% 90% Puti
Inspiration VC VC VC Expiration
Volume
Figure 5-31. Graph of flow-volume spirometry.
Siiigle Breath Cloiittg^olrtiiSe; ' i..
Like the mid- and end-expiratory flqw measurements described above, this test is thought to
be a simple and accurate indicator of early airway dysfunction- The procedure measures the
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U.S. Naval Flight Surgeon's Manual
dilution of residual nitrogen in the lung after a single breath of 100 percent oxygen. Airway
dysfunction and collapse give a characteristic uneven dilution profile through expiration.
Diffusing Capacity
fMk test does not depend upon airway function but rather measures the permeability of the
alveolar capillary membrane by use of carbon monoxide inhalation and uptake measurements. It
is useful in describing dysfunction in interstitial diseases of the lung such as sarcoid or the
pneumoconioses. It can be of help in following the recovery of a pilot from a reversible
disorder, but has little screening potential.
Arterial Blood Gases
These measurements, particularly if done at near maximal exercise, give a good indication of
overall pulmonary function as ventilatory, diffusing, and perfusion capabilities of the lung all
come into play. The normal response to exercise is to maintain a normal PO2 and PCO2 at all
times. This can be helpful in Confirming recovery from lung disease prior to returning a pilot to
flight status.
Aviation Effects on Pulmonary Function
The safe and effective operation of a combat aircraft stresses the oxygen delivery system to
its Umits. Oxygen demand may rise by a factor of 15 in certain high performance situations.
Some of fliis demand is met by a greater extraction of oxygen from the hemoglobin (the shape
of the oxygen-hemc^obin dissociation curve allows this to happen with a minimal drop in
PO2). However, much of this demand must be suppKed by an increased cardiac output coupled
with an increased pulmonary oxygen delivery.
The pulmonary role can be divided into several steps. First, adequate oxygen must be
available in the env&onment. Secondly, airways must be open and functional. Thirdly, the
alveolar capSQlary m^brane must allow efficient diffusion of oxygen. And lastly, pulmonary
blood flow must not only be of a sufficient magnitude, but it must be appropriately matched to
ventilated alveoU-
Immediate or Short Term Effects
High G-Forces. The effects of a high G-force can alter several of these pulmonary functions.
First, it can both reduce, as well as redistribute, pulmonary blood flow to dependent lung fields.
Secondly, it can cause collapse of these same dependent lung fields (ateletfrasis). The net effect
of these alterations is both a decrease in vital capacity and an ineffective matching of blood and
air, producing a significant compromise in the lung's ability to deliver oxygen.
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Internal Medicine
Chest Constraints. Chest constraints have a small but significant effect on pulmonary
function. The vital capacity is somewhat decreased and the work of breathing slightly increased
by these de\ices.
Oxygen-Delivery Systems. Oxygen delivery systems are needed to maintain an adequate PO2
in the inspired air while flying at altitude. However, the dryness of the gas, the slight positive
pressure, the possibility of contaminants, and perhaps the direct effect of 100 percent oxygen,
all contribute to airway irritation and transient airway flow measurement abnormalities
following jet flights. Oxygen will also accelerate the high G atelectasis described above, as it will
be absorbed completely from closed-off alveoli.
Long-term Effects ..k; ;." „■ .. ■,.< ■ » li* - -^v: .
It has always been thought that the vital capacity and flow measurement decreases
immediately post flight reflected a totally reversible situation. Indeed, atelectasis, chest
complaints, and volume-time spirogram abnormalities generally are resolved by 12 hours post
flight. There are new pathologic and physiologic data, however, that suggest that progressive,
subtle^ and pemitfi®n* ^^banges are^^i^ luogs of jet aviators. What tiie @li#Li^6
faetors are and what relationship, if any, these changes have t^f shrt^eitof ^i^leaee remTO
be explained.
Asthma
lissthwa is. a . stale of > bronchial hyperreactivity to a number of stimulants. The classical
childhood variety results from a characteristic IgE allergic phenomenon. The less well
understood "adult" variety develops later in life, has a less clear relationship to allergies
(although nasal polyps and aspirin sensitivity are common), and seems more related to
prolonged environment^ stresses ^eh . as (teinic m^ImM^ ittioking, physical/chemical
irritants, and anxiety states.
Aciite Attack 6f Aithmtf • ' . .. > n.. ir. , .. .
Bronchospasm can develop, rapidly and may be acutely incapacitating. The "Ifi^er," tho»#
often apparent, may not be readily appreciated. Relief of the bronchospasm is best
accomplished by
1! e|)ir|ephrine (1:1000) - 0.3 cc subcutaneously q.20 minutes x three
2. aminophyUine - 500 mg over 20 mmutes LV., followed by a 0.5 irig/kg/hr. LV. drip
3. 100 percent oxygen by mask
4. inhalation of a ^2 stimulator
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U.S. Naval Flight Surgeon s Manual
5. removal of the "trigger" — i.e., treatment of the infection, removal of environmental
factor, calming of the anxiety state. In regard to this last point, mild sedation may be
helpful but should be used cautiosly as respiratory drive depression may result.
6. steroids such as 1 gram Solu-Medrol LV. in difficult cases
7. intubation and mechanical ventilation if the patient is tiring. A ri&ing PCO^ is a sensitive
indicator of this.
Prognosis and Approach to Asthma in Aviation
Most childhood asthma will spontaneously regress by young adulthood, but Navy
regulations disqualify any candidate whose symptoms have persisted past the age of 12. On the
other hand, adult asthma develops in the age group containing already -designated aviators. The
future of such an individual is a difficult decision for the Flight Surgeon; In general, adult
asthma usually stahUizes or improves with age, although a significant percentage go on to
develop chronic obstructive disease. Furthermore, the clinical picture runs a wide spectrum of
severity. Thus, the approach should be indi\idualiz;ed. The pilot with mild symptoms once a
ye® during a bout of the flu, and with normal pulmonary function tests off medications the
remainder of the time, need not be permanently founded. Conversely, severe attacks,
permanently abnormal pulmonary function tests, and a need for chronic medication all
constitute reasons for disqualification.
Spontaneous Pneumothorax
Although uncommon, the acute spontaneous pneumothorax can strike any age group
unpredictably and be acutely debilitating. Aviation candidates at risk (e.g., bullous disease,
history of pneumothorax in previous three years) are disqualified before entry into the flight
program. Nevertheless, this does not eliminate aU those at risk, for example, those with the
presumed congenital alveolar defects that are not detectable clinically.
The acute episode may range from a sudden, mUd pleuritic pain to a full cardiopulmonary
arrest. Rest and analgesia are often aU that is required for small pneumothoraces, but a chest
tube for reexpansion may be required if large or seriously symptomatic.
Following a single, spontaneous pneumothorax, the risk of recurrent pheumothorax is hi^
for at least one year (up to 30 percent). Because of this, aviator^ ^ould be pounded for at least
this period of time. A second pneumothorax is permanently disqualifying, Unless surgical
stripping or adherence of parietal and visceral pleura is done. In those postsurgical cases,
exercise tolerance and pulmonary function testing must be normal before the patient is returned
to flight status.
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Internal Medicine
The air evacuation of patients with pneumothorax is discussed in Chapter 17 , Aeromedical
Evacuation.
• ■ I- 1 1 ■ .(!■■ I . , ^ , ,. , . .. 1 •.,,,11.
Sarcoidosis
This is an interesting granulomatous disease of unclear etiology. It frequently presents as
asymptomatic bilateral hilar adenopathy in rounne chest X-ray. T.tei^ease, however, can
pro'diiW Wfetitiffl' Ml^ ySletey etytiiema nodosum, uveitis', ftLm^tA' aMbim0&es, and
dept^W 'oi Millar iftiMtiftafsri l^^rtsfeWk, hdne tesfQH^ splenortltif aly Wi' ft«afil3^i&'
symptoms are rarer. Diagnosis is made by biopsy (non-cascading granuloma). Asymptomatic
hUar adenopathy alone is virtually diagnostic of the disease.
Acute sarcoid occurs in young adults and most will completely resolve within two years
^6itt'8%ebe. SfeVMH mdy heil8feM^ffii^tt#lfeftt1fe<5iWfr«a 6f 8ym^t'<5lAfer to6wing such "a
course, a return to flight status is reasonable providiftg exercise tokrance, pitlmonftry fbif^tidti,
and all signs of the disease have returned to normal.
The more insidious and chronic form of sarcoid occurs in an older population with more
severe pulmonary and extrapulmonary symptoms. Prognosis here is poor with few remissions.
These individuals are generally disqualifled from aviation.
Pulmonary Emboli
Emboli to the lung can result in syndromes ranging from mild acute pleuritis to an acute
asthmatic attack to a sudden new supraventricular tachycardia to a cardiopulmonary arrest. The
diagnosis should be suspected in those predisposed to thromboemboli (e.g., venous disease,
autoimmune phenomenon, right heart endocarditis) in whom acute pulmonary problems de-
velop. The diagnosis is made by a good history, findings of pleuritis, arterial oxygen desatura-
tion, and evidence of a lung perfusion defeet on scan or arteriogram. The treatment is primarily
mmed at prevention of recurrence through anticoagulants. Oxygea and bronchodilator therapy
will improve oxygenation and ventilation/perfusion dysfunction secondary to the emboli. A
special form of pulmonary embolus, a fat embolus, should be suspected if acute pulmonary
compromise occurs 48 hours after major bone trauma. In this case, heparinization is contra-
indicated as it would produce more necrotizing fatty acids. Rather, missive steroids and
diuretics (severe membrane leakage occurs giving pulmonary edema) are needed.
The aviation future of individuals post emboli depends on two things. First, there must be
no residual cardiopulmonary dysfunction as determined by exercise testing, puhnonary func-
tion, and 24-hour EGG monitoring. Second, the source of the emboli must he completely
resolved.
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U.S. Naval Flight Surgeon's Manual
Airway Bums
Hot irritant gases such as ammonia, nitrogen oxide, sulfur dioxide, and sulfur trioxide are
common in smoke from burning material. Phosgene is another toxic irritant gas that is produced
when carbon tetrachloride from fire extinguishers comes in contact with hot surfaces.
AjEW^f burns are produced by these substances when inhaled. The clinical ^ctrum ranges
ftom mild pain, dyspnea, and causing to severe pulmonary edema and "shock hing."
Furthermore, these serious compHcations may not appear until 3 to 72 hours after exposure.
Therapy is supportive in mild cases, but observation for decompensation is warranted.
Should a "shock lung" syndrome develop, oxygen, diuretics and massive steroids are indicated.
Return to flight status is reasonable when symptoms clear, and testing of airway function
and diffusing ability have returned to normal.
5-84
Internal Medicine
SECTION VO: RENAL DISEASE '
Signific^t renfd disease in the avisatiow • e©mm«nit|f- is limiterd to acute infectidn,
asymptomatic or gymptomatic hematuria/proteinuria, and nephrolithiasis which, if recurrent,
may be disqiiplifyia|,
It is i^e for a male under tiie age of 50 years to get urinary tract infection (Wintrobe et al.,
1974). Otfepr infectious processes such as gonorrhea and prostatitis should be ruled out. With
clinical evidence of pyelonephritis, an obstructive process must be ruled out with an IVP. The
infecting organism should be documented with cultures, and sensitivities should be obtained to
guide antibiotic selection. Gantrisin, 1 gram p.o. q.i.d,i with inereased hydra#Ba,^<>!e AmpiciUih
500 mg |i;o. q.i.d. lor 14 days, are frequently appropriate fii;st treatment drugs. Repeat urine
cultWIg8,»after three days of therapy will demonstrate the seifBetiveness of in vivo antibiotic
action, and a culture three days after completion of therapy will insure eradication of the
infection. The aviator is grounded until 24 hours after completion of therapy. With recurrent
infections, infection with an unusual organism such as Proteus or Pseudomonas, or evidence of
obstructive process, referral for complete urological evaluation is recommetided.
Hematuria/Proteinuria
The discovery of hematuria/proteinuria in an asymptomatic individual on routine Screening
urinalysis requires that an etiology be determined. InitiaUy, lht tiSj should be repeated;
that proper collection teehiuqme is follewed, A thBee^hottle mH^tiom Kay be helpi|il;^li^rt®
idea that the upper tract etiology will show consistent abnormality with the lowiRltraet only at
the beginning or end collection. Benign etiologies include postural proteinuria, proteinuria
following intercourse, and hematuria/proteinuria following vigorous exercise and certain febrile
illness (Wintrobe et al., 1974). Infectious process is the most common etiology. Other etiolo^es
in order of decreasing frequency include neoplasm, trauma, calcuU, glomerulonephritis, aiid
bleeding disordere. Evaluation of blood urea nitrogen, ^mm creatinine, 24-hour urine for
creatinine, total protein, and total volume, serum uric acid, serum protein electrophoresis,
serum complement, fluorescent antinuclear antibody, prothrombin time, partial thromboplastin
time, and IVP gives an assessment of renal function and some diagnostic information. In
symptomatic patients and if necessary to establish the diagnosis in asymptomatic patients, the
aviator should be grounded and promptly referred to a urologist or nephrologist for dotttplete
evaluation.
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U.S. Naval Fli^t Surgeon's Manual
The aviator's status is dependent upon the underlying disorder, -.g.. a glomerulonephritis
may be self-Umiting, and the aviator is returned to flight status, whereas a progressive neoplasm
,of the bladder will render a patient permanently NPQ.
Nephrolithiasig
Nephrolithiasis m a vexing problem in the aviation community. The risk to be appreciated
by the Fhght Surgeon is sudden incapacitation in flight and applies with equal importance, but
differmg implications, to all aircrew. In symptomatic in^ividiJals, gtone analysis is mandatory
along with evaluation of hematocrit, hemoglobin, white blood count, serum michim,
phosphorous, blood urea nitrogen, serum creatinine, and urinalysis with culture and sensitivity.
AdditionaUy, an IVP and urology consultation should be obtained. If no stones are found and
the workup is negative, the aviator may be placed in an "up" status.
If the workup is positive and the underlying process is treatable, the aircrewman may be
placed in an "up" status after treatment.
an IS
If the workup is positive and the underlying process is not treatable, the aircrewm
permanently grounded. In the case of recurrent kidney stones, he is likewise permanently
grounded.
When a stone is found accidentally in the asymptomatic aircrewman with no previous
history of stones, a complete workup as above is required. Additionally, an opinion from a
urologist regarding the likdihood of the stone becoming a significant problem should be
obtamed. Then a decision regarding the individual's flight status can be made at a local level or
refeiwd to the Specisal Board of Flight Surgeons.
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Iiitenial Medicine
SECTION Vni: M4LIGNANCY
With ejHlier delecttbii ol^«talignancfeSeorHbined vii&i improved arad a^essive combinations
of surgical therapy, chemothferapy, immunotherapy, atid/@r radiation therapy, there are
increased numbers of long-term survivors and apparent cures (e.g., Hodgkins lymphoma).
Moreover, there is expected to be further improvement under present investigative programs.
Survivors of childhood cancer will often have a residual physical deformity, however, that
renders them NPQ for aviation (Li & Stone, 1976)/F6r sUrvlvorMtftout physical impairment,
individualization of each case to type of tumor, therapy given, current prognosis, and need of
Ijif aviation community will have to be considered. Ideally, entrance into the aviation
community will require that the patient be considered permanently cured after more than five
years post- definitive thesfipeutics with no residual physical impairment.
The designated aviator who is one year past a major therapeutic program, considered a
permanent cure, and ^ffi-ii^ i^^tl^ d%idaM^Srigflfytfd#i^^^
for placement back to physically qualified status.
References
American Thoracic Society. Preventive therapy of tuberculosis infection. American Rsuieiv of Respimtory
Bweoie, 1974, 110.
Bruce, R.A. Exercise testing of patients with coronary heart disease. Principles and normal standards for
evaluation. Annals of Clinical Research, 1971, 3, 323-332.
Castell, D.O. The lower esophageal sphincter: physiologic and clinical aspects. Annals of Infernal Medicine,
1975,53,390-401.
Department of th<' Navy, Bureau of Medicine and Surgery. The diagnosis and management of tuberculosis
(NAVMED P-5052-20). Washington, D.C., 3 February 1973.
Department of the Navy, Bureau of Medicine md Stttgery. TubeiGidiOsfe program (MJiiffiDMST
6224.1D). Washington, D.C., 8 Augtst 1975.
Dienstag, J.L., Routenberg, J. A., Purcell, R.H., Hooper, R.R., & Harrison, W.O. Foodhandler-aesodated
outbreak of Hepatitis Type A. Annals of Internal Medicine, 1975, 83, 647-650.
Farmer, R.G., & Brown, C.H. Emerging concepts of proctosigmoiditis. ©iseatfeS of f ftfe Gohnan^Reemm, 197#,
15,142-146.
Gitnick, G.L., Goldberg, L.F., Kore«,ft.v^***BhVJA'PwU¥Wand.antigen8 ofhep of Internal
MedtciW, 1976, 85, 488496. , . . ,
Gregory, P.B., Knauer, CM., Kempson, R.L., & R*ite©id Hietapy in severfe vii!ifl hejjatlfe. New Enj^and
Journal o/itfedioine,. 1976, 394,681-687.
Johnston, R.F., & Wildrick, K.H. "State of art" review, the impact of chemotherapy on care of patient with
tuberculosis. American Review of Respiratory Disease, 1974, 709, 636-664.
Jones, S.R., Binder, R.A., & Dewtiwlid, tlM, Ju.- Sudden death in sieWe-cell tr^it. JVew England Jmmd of
Medicine, 1970, 282, 323-325.
5-S7
U.S. Naval Flight Surgeon's Manual
Leayell, B.S., & Thomp, O.A. Fundamentals of clinical hematology (3rded.). Philadelphia: W.B. Saunders Co.,
1971.
UvE, & Stone, R. Surviyors of cancer m childhood. Ani^ of lt^^mwdMedicitfet 1976, 84, 551-553.
Msamoni11JJs..Pnustical ekctfoeardiograp (5th ed.). Baltimote: The Williame and WSkins Co., 1972.
Second East African/British Medical Research Council Study. Controlled clinical trial of four 6 month regimens
of chemotherapy for pulmonary tuberculosis. American Review of Respiratory Disease, 1976, 114,
471475.
Slpm,MMf(^nki^gm^^ New Yoik: The Macmillan Co*^ 1970.
Szmuness, W., Dienstag, J.L., Purcell, R.H., Harley, E.J., Stevens, C.E., & Wong, IXC. Distribution of antibody
to hepatitis A antigen in urban adult populations. iVeic England Journal ofMedicine, 1976, 295, 755-759.
ViUarejos, V.M., Yisona, K.A., Gutierrez, D.A., & Rodriguez, A.A. Role of saliva, urine and fever in the
transnrission of Type B hejjatiliB. Net^ Ei^ifdJomml &f MgtUfitne, 1974, 091, 1375-1378..
Wintrobe, M.M. Size and hemoglobin content of erythrocyte; methods of deteitniiiatioa and clinical application.
Journal of Laboratory and Clinical Medicine, 1932, 17, 899-912.
Wintrobe, M.M., Thorn, G.W., Adams, R.D., Braunwald, E., Isselbacher, K.J., & Petersdorf, R.G, (Eds.).
^^mfaiR'»Rrbu2^les of internal medicine (7th ed.). New York: McGraw-Hill Book Co., 1974.
Wright, H.F., & Wilmore, J.H. Estimation of relative body fat and lean body weight in a United States Marine
Corps population. Aerospace Medicine, 1974, 45, 301-306.
Bibliography
Abramowicz, M. (Ed.). Handbook of tmtimicrobial therapy. New Rochelle, N.Y.: The Medical Letter on Drugs
and 'Hierapeutifis, 1976.
Bates, D.V., Macklem, P.T., & Christie, R.V. Respiratory function in dikease. MaMpUa: W.B. Sauftlbts Co.,
1971.
Beall, G.N. Asthma: New ideas about an old disease. Annals of Internal Medicine, 1973, 78, 405-419.
Beeson, P.B., & McDermott, W. Textbook of medicine (14th ed.). Philadelphia: W.B. Saunders Co., 1975.
Benchimol, A. Vectorcardiography. Baltimore: The Williams and Wilkins Co., 1973.
BeOrti^; n.M. A ten year T«<riew of ^ontaneons pneumothorax in an Aimed Forees hospital. American Review
of Respiratory Disease, 1964, 90, 261.
dark, J.M., & Lambertsen, C J. Pulmonary oxygen toxicil^, a review. Pharmacological Review, 1971, 23,
37-133.
Dalen, |.E., & Alpert, Natural history of pulmonary emholiem. Progress in Ci6-iMtnmteukr'I>iswmii9^5i 17,
259-270.
Department of the Navy, Bureau of Medicine and Surgery. Manual of the medical department (NAVMED 117).
Dreifus, L.S. (Ed.). Cardiovascular problems associated with aviation safety: Ei^th Bethesda conference of the
'iABterieane(EdI^ofCar#>logy..j4nimcon/o«i7w/^o^ i
Dustan, H.P. Evaluation and therapy^ of hypertension. Modem Ciiite^it^ of CarStovascu^ Disease, 1976^ 45,
97-103.
Elngie, M.A. (Chairman, American Heart Association Congenital Heart Disease Study Group). Resources for
optimat lbng term care of congenital heart disease. Circu1atio«f l9^1t44i A205.
588
Internal Medicine
Fajans, S.S., & Sussman, K.E. Diabetes meltitus: Diagnosis and treatment (Vol.111). New York: American
Diabetic Association, Inc., 1971.
Ferrer, M.I. Electrocardiographic notebook (4th ed.). Mount Kibco: Futura, 1973.
GaUe, W.D., & Townsend, F.M. Lung morphology of individualB exposed to prolonged intwmittent
supplemental Aerospace Medicine, 1962, 33, 1344-1348.
Grieco, M.H. Current conceptB of the pathogenesis and management of asthma, bulletin of the New York
Aaidemy of Medicine, 1970, 46, 597-610.
Harrington, Wj., Reiss, E., & Bocles, J.S. (Eds.). Fundamental and clinical aspects of internal medicine.
Endocrinology and Metab0liam. Miami, FI.: University of Miami School of Medicine, 1975.
Ho, B.L. A case of spontaneous pneumothorax during flight. Aviation, Space, and Environmental Medicine,
1975,46,840-841.
Hai«t J.W. fhe ftewt. New York:. McGraw-Hill Book Co., 1975.
James, D.G. Modern concepts of sarcoidosis. Chest, 1973, 6$, 675.
Jones, N.L. Exercise testing b puhnonary evaluation. New Enf^and Journal of Medicine, 1975, 293, 647-650
and 864-865.
Kaufman, R.E., & Wiesner, PJ. Non-specific urethritis. New En^nd Journal of Medicine, 1974, 29J,
1175-1177.
Kilboume, E.D. (Ed.), Iaflu0ma virus and influenza. New York: Academic Press, 1976.
Killen, D.A., & Gobbel, W.G. Spontaneous pneumothorax. Boston: Little, Brown, & Co., 1968.
Koch-Weisser, J. Common poisons. In M.M. Wintrobe, G.W. Thorn, R.D. Adams, I.L. Bennett, Jr.,
K j. Issdbacher, & R.G. Peteradorf (Eds.). Harrison's principles of infenud meiicirte (6tti cd.). N«w Yptk:
McGraw-ffll Book Co., 1970.
Lagdon, D.E., & Reynolds, G.E. Postflight respiratory Bymptoms associated witii 100% oxygen and G forces.
Aerospace Medicine, 1961, 32, 712-718.
Laragh, J.T. (Ed.). Hypertension mttnual. New York: Yorke Medical Books, 1975.
IVboklem, P.T. Diseases in small airways. Batuss of Respinttory Disease, Ameriean Thoracie Soekty Newt, 1976,
2, ^29.
Resenkov, L. (Ed.). The cardiac rhytiim disturbances. Medical Clinics of North America, 1976, 60, Part I and
Part n.
Sanford, J.P. (Ed.). Guide to m^icrobkd Iheinpy. Dallas: Infectious Disease Service, Department of Internal
Me^Kdne, UniVieiBity of Texas, South Western Medical School at Dallas, 1975.
Schlueter, D. P. Response of the lungs to inhaled antigens. American Journal of Medicine, 1974, 57, 476491.
Siltzbach, L.E. Sarcoidosis: clinical features and management. Medical Clinics of North America, 1967, 51,
483.
Standards for cardiopulmonary resuscitation and emergency cardiac care. Journal of fhe American Med&^d
Association Supplement, 1974, 227, 833-868.
Stein, M., & Moser, K.M. (Eds.). Pulmomuy thromboembolism. Chicago: Year Book Medical Publishers, 1973.
5-89
o
I
o
CHAPTER 6
l^tGHIATRY
,t
The Context
The Psychology of Flight
The Psychopathology of Flight
Psychopathology in the MiUtary
Psychiatric Evaluation
TreatHient ModaHtifiB
The Psychology of Survival
References
Bibliography .-' v •
Appendix 6- A. Ouiin^ for Psychiatric Reports ' . : .
APiPsndix 6'B> Psychological Testing "J
TheCoiitesit "1'' ' '
A 23-year-old, Lieutenant (Jg) Naval aviator, flying an F8 Crusader
fighter, is returning Jo his ship with ,20 minutes of fuel remaining.
Following instructions from the ship and making a radar, carrier-
^Mtiyll^' approach (CCA), he turns four miles astern the ship to
make his final approach. His altimeter reads 500 feet when he is
informed that the ship 's height-finding radar is inoperative — meaning
they can't tell him for sure how high? he fe over the Water whiek*he •
can't see. He's in solid fog and overcast untU one mile astern the ship,
when he breaks into the clear 300 feet over the water. Now flying at
' ■ 140 knots, he glances at the "meatball" hght on the carrier deck,
' *v^h tel» Hiiaf^tfM is about on gUde path. The red glare of the
oxygen warning light gets his attention for two or three seconds. He
asks himself, "Could the gauge be inoperative, the fitting defective;
should I simply jerk the mask off? Sure, I don't need oxygen at this
altitude. Better check the meatball again — fallen too low — headed
directly for the carrier ramp — add full power — too late? No coming
up — thank God! — now try to land this beast - missed the first
wire second- thtttf-^i I*# h^a It!' W/ eaii^^^^^^ f^^tff. M
Stop. Cut powet." r-' in-
— from Fear of Flying by
Captain Roger F. Reinhardt, MC, USN
6-1
U.S. Naval Flight Surgeon's Manual
The Psychology of Flying
"When I strapped that A-4 on, it wasn't the A-4 that was flying, it was me flying up there all
over the sky."
That A-4 pilot is saying that flying is rea% m natural as breathing and fun to boot. His
airplane became a part of him. Curiosity, exploring, is a basic and compelling human drive, and
flying is one of the best expressions of it.
But people fly, especially in the military, for other reasons, too. The reasons of particular
concern in aerospace psychiatry are those which are neurotic. They can be healthy or
maladaptive and motivation for flying is a mixture of these two - natural and neurotic.
For those who are naturally drawn to flying, there seems little else in the world as exciting
or worth doing. For those who fly for more neurotic reasons, it can be thriUing or at least
satisfying, but it can also be fraught with anxiety which must be defensively dealt with, either in
a healthy^ adaptive manner or maiadaptively. It takes perhaps a Ml of tiie obsessive-cdttipuMve
temperament to endure the tedious patrols of a P-3 or a bit «rf the hjiteric to risk life and limb
as an F-4 pilot. When, however, these defensive colorings of character become over-stressed,
they turn maladaptive, and psychopathological responses to flying are encountered.
The Psychopathology of Flying
Psychopathology means the existence of any of the symptoms (uncomfortable feebngs) or
signs (abnormal behavior) listed in the Diagnostic and Statistical Manual of the American
Psychiatric Association. The psychopathology of aerospace medicine is no different from that
found in any other area &f Vtmsg. What is dif^guishing is the context in which it arises - the
stresses peculiar to military flying. Tliese include moving in the cSmension of space,
complex, high performance aircraft, adverse weather, frequent family separations, combat, the
one-to-one student-instructor relationship so conducive to transference and countertransference
phenomena, the responsibihties of command, and the return to operational flying after long
absences occasioned by intermittent staff assignments, schools, or instructor billets.
A few fli^t students experierice probieins with space, becoming one with the drcraft, or
with the responsibility of solo fli^t. The most common difficulty involves the student-
instructor relationship. The most common symptoms are airsickness, anxiety, forgetting
procedures, gastrointestinal complaints, and depression with its somatic equivalents.
6-2
n
Psychiatry
In the professional years, self-esteem is more at stake, with conversion and psycho-
physiologic symptoms the rule. The conversion symptoms usually involve the special senses
required to fly - eyes, ears, and^ ibllllMGe- If psychophysiologic symptoms presettif j|hs ptttit Is
usually hi^jittotii^ated to continue %ing,«jd this ie«|i\heili»wtd if
threatened. Phobias do occur, but are uncommon. If anxiety is present, it is usttially more
directly e3|pfesgfid9&#iraBlefsfirioffl|il^t, ..>,■ - .
Accident proneness may emerge at any time. It is currently considered to be the result of
the character traits of extreme sensitivity to criticism with a pei^li^t ltttlilQQg wtemotipni^
upset, or the result oft;^fjpf©ssii^,; wpi^ve life eh|!^gs,.»frf;ft!fc|#e tWtpl^
carelessness. The patiejxt may send out i»ramings in the form of persoRaK^ chwiges or minor
blunders in various areas of his Ufe.
As the years pass and the pilot becomes a senior aviator, depression or alcoholism are more
apt to be encountered. When retirerttetti%fiteiaMeal,'tfeise symptoni^'»# soiaitf*ffiesi ttte^d to
as
The thrill of flying sustains the aviator and the flight officer through their careers. It
dechnes through the years, slowly at first, precipitously around thirty, then slowly again. Side
by side with the thriU of flying and the fulfillment of belonging to an elite group, there
gradually emerges a recognition of the limitations of aircraft, of the dangers, and of family
responsibilities, resuM^ in some realistic, conscibus anxiety. The balatic^ of these two — thrill
and anxiety, the "love achd fear" — determines, at any point, the motivjiyw'M'MnliBiife. The
point to be made is that if a young student complains of anxiety or any of its myriad
manifestations, something is wrong, and intensive evaluation is indicated. But, if the senior
aviator presents with similar complaints, it may not necessarily be abnormal. It is normal for
him to be aware of mtHe eom(Aom skMe^i W mi^'^t M
TenttJition of the'lte^^W#%teWi^ i^iteoilM dlseus^on to help hirrif M& ftieds^d
arrive at a matifrfe Mt|' b&'A^itWiSiequired.
■ r.-i :c i • . •
Pressure from sources other than flying may also arise and interfere with it. Marital
adjustment is probably the most common. Captain Frank Dully, MC, USN, points out in his
lecture, "Sex and the Naval Aviator," i«-1t'iti&A M'dl«5diiM^ li «k6 fe#t^
and in his hoflie. iriTlflffirl^''^ cmm and'thefei^%a^'tet^i4d&d^^^^^^ and
affect the other area. Syrii|>tSiitis'ltftd^ Mpaired flight performance can result. Occasionally,
however, flying may be the only conflict-free area and a haven of respite in a troubled life.
6-3
U.S. Naval Flight Surgeon's Manual
Koause of the close association between the Flight Surgeon and his men, they may be
mlsarrassed to explore marital problems with him. One Flight Surgeon found it worked quite
w#>t|> t»adi Bfaa!4Pons with his eountefpftrt 'Whm it OjtOle to treating problems of this sort. A
feeling of confidentiality was better preserved, and treatmeBt was more successful.
Combat, with its acute dangers, aggressions, and honors, may call for the full gamut of
defenses. This can range from first line defense mechanisms, such as the denial,: "It can't
happen to me," or the projection "I'd never pull a stupid stunt hke that," through compulsive
preflighting, counterphobie daring and carelessness, and somatizations, all the way to an acute
psychotic break. The FH^t Surgeon muSt take the context into cohsideration, and treatment
calls for the time tested principles of immediacy, proximity, md expectancy.
Psyckopadiolojpr in lite MOitai^
Military people are shaped partly by the constraints of the military environment, but they
also choose that environment to meet their intrapsychic needs. Most officers and men function
proudly and well. Only the legendary five percent create the equally legendary ninety-five
percent of the administrative vexation in a command.
By far thfi. jnost- conimon source of turmoil and discontent is the passive-aggressive
pil^ippality. He comes tailorpiMle to awfi^, engaging in constant battles with authority^ He
,ettt^s the Navy hoping for better and finds worse. An unsuitability discharge is the only
ij^erapy he will accept.
Very dependent people enter the Navy optimistically, but a few cannot tolerate the
separation from home or meet the demands for mature, responsible behavior. Fewer still arfe the
persons , with borderline personality organizatioii and narcissistic personalities with antisocial
traits. Rarely can these people fUnetion effectively. They usually are adminis^tfati^seily s^s^rate^
either for unsuitability, if they are recognized early enough, or for misconduct if too late..Tll^
are unmotivated for military service and, therefore, for therapy, which at best carries a very
poor prognosis. . ,
. 0<Kca#oiwIlf» well-educated or hi^y intelligent young enlisted men become unhappy,
hmp^, resentful, and unable to fiinction. Unfortunately, there is no administrative relief from
their particular problem, and they may become mired in disciplina^ diffieulty for the first time
in their lives.
There are many real stresses to which the enlisted ilian is heiriihe resulting psychopathology
is properly labeled as an adjustment reaction of adult life (manifested by the presenting
64
Psychiatry
symptoms and signs). Pay insufficient to meet the needs of a burgeoning famUy, moves,
^separations, combat, moonlighting, and frequent watchstanding are just a few of the stresses.
These stresses are usually met at a relatively young age and with few educational, emotional,
family, md financial lelourpei, A social worlpr, if available, is often better able to handle these
real rather than, iwtrap^tJhic ^ftrepes than the psychotherapist Flight Surgeon.
Alcoholism is as serious a problem in the Navy as it is elsewhere. Approximately one
individual in ten over the age of 21 will become a problem drinker or alcoholic. Since it takes
about ten years to manifest the disease, about one person in a group of one hundred officers
and men will be suffering from it at any one time.
Diagnosis can be aiffi<3«lt. , One of the signs is that the patient can no longer control his
drinking; he cannot plan or predict where, when, or how he will drink. Another is that his
drinking is detrimental to his health, his marriage, his family life, his social Ufe, or his
occupation, and he cannot stop.
The definiiisin, diagnosis and detoxification procedures for alcoholism as well as the Navy's
rebi^ilitation prjogram are discussed in detail in Chapter 19, Alcohol Abuse. The procedures to
be followed when rehabilitation is unsuccessful are outlined in Chapter 16, Disposition of
Problem Cases.
Following rehabilitation, psychotherapy may or may not be indicated. The persistence of
pisychopathology (symptoms and signs) ivill be decisive in this regard. The patient should be
helped to plan and/ or maintain his own program of sobriety. If he is in a flight billet, the Flight
Surgeon must follow the dictates of BUMED Instruction 5300.4 of 19 April 1977 regarding the
procedure to be followed for ultimate return to fuU flight status.
Although the problem of drug abuse is less pervasive, the success of its treatment is m<jre
uncertain. Often serious personality disorder is involved, particularly in the younger person. TFj^fi
treatment for that is problematic at best. If drug dependen(?e k qyi4ent| the first step is to place
the patient in a program designed to assist him in becoming and remaining drug free so that
psychotherapy may be pursued if indicated. One author recently estimated that about
45 percent of poly-drug abusers in his study showed evidence of reversible brain impairment
that precluded their effective cooperation in any sort of jgsycholhej'j^y f or a pii^^^^ of week?
after they were dftig free. Current Navy inslracfiotts Mffi^'llmt A
dependent be subjected to a minimum of 30 days of rehabilitation regardless of their ultimate
disposition. The administrative discharge for drug abuse is discussed in Chapter 16, Disposition
of Problem Cases.
U.S. Naval Ilj^t Surgeon's Manual
Psychiatric Svabiatioii
Flight Surgeons are faced with assessing, as accurately as possible, the ever shifting balance'
of natural and neurotic motivations for and attractions to flying. This balance is mirrored in the
physiological or pathological alterations which appear as pUots, NFO's, and aircrew or
applicant and Studisnts apply for and undertake flight training or later run afoul of nature's
laws and human nature's intrapsychic forces, the contexts for maladaptations to flying. This
task is approached by uncovering these contexts in the life of the patient and by evaluating his
mental and physiological responses to and abUity to cope with the balance of intra- and
extrapsychic forces impinging upon him.
There are two time-honored approaches to the psychiatric interview: The first, preferred, is
to elicit a spontaiieous unfolding from the patient of Ms troubles; the second is directj
structured questioning by the psychiatrist.
Painful, embarrassing, frightening feelings are troubling the patient. By skillfully, judiciously
easing his need for defenses and drawing these feehngs out, soon the whole story or pattern of
his aiffieuldeg m living will luifbld, the bits and pieces falUng into place. But if defenses are
ri^, sta<i imf ottmt ietgSls are mis^ng, the pattern must be laboriously reconstructed by the
ekaittiiieir fiftont a te^ous, stultifying question and answer history-taking. The physician may gain
insight, but the patient does not, and he also gets little relief.
An evaluation is an artful combination of these two approaches — eliciting spontaneously
and tracing the patient's painful feelings, and laboriously extracting the dry details of his
ptmitt md pi^t life. Together, ideally, they should lead to a coraprehensiltfe picture of his
emotional illness.
Emotional illness almost always occurs in the context of social interaction when core
conflict-tri^ering persons or situations arise. These situations very frequently represent major
Mfe ehangfes bit crises related to the milestones or maturational tasks reflected in the phases of
thfe |»tjrchdsexnal/p8ychosocial scale of development, e.g., dating, ^aduating, occupational
choice, marriage, parenthood, entiance into the military, retuim to civilian life, etc. The need to
suppress painful affects, forbidden impulses, or the memory of tiife original core conflict or
fantasied elaborations of it leads either to defensive symptom formation or defensive, immature
behavior. If inefficient, the defensive symptom formation appears as psychotic or neurotic
MiaiefeS, The deffehSivfe, immature, behavior, when persistent, appears as "character neurosis" or
peraonaEty disorder.
6-6
Paychiatiy
In the ideal situation, there should be evidence of defensive, painful affect, forbidden
impulse, or core-conflict situations at several points in the past history, including the original
situation, the present Ulness setting, the mental status examination of the psychiatric interview,
and finally during the treatment «ft*» #i#«<Mfffiim felttttta^ed md i
In any psychiatric eviduation, an in^aiilii^M with structure is desirable to obviate
overlooking some important aspect of a patient's problem, to make sense of it, and to present it
in a concise, credible fashion for others who must make decisions based upon it. Ideally, this
format should bear some resemblance, as well, to what it is to be human. The format at NAMI
was designed with these considerations in mind. -fUyiji . ■>• n
The art of writing A good psydhitttric ^g|^oWis*k*p^M^M M W<^'i^ifl^^
occur in a specific context to a somebody who by virtue of an idiosyncratic weakness is
unusually vulnerable to that particular context at that particular moment in his Ufe. The
meaning of symptoms is discernible only in the context; they have no meaning in and of
themselves (Langs, 1973). That they happen to a somebody requires that a report reflect in its
ire, especf^t itt^^'^S^'ttf fi^|(^^rtfdh, #fet!t ii t# Be human. The point of departure
pilttfftiSi&h iff always the defense, the symptoms or signs that led to psychiatric refeital.
The elements of the write-up are points in the patient's life that are re-enactments with
significant others of the core conflict that give rise to his defensive personality patterns. A core
conflict is a conflict inherent in, and basic to, a psychological developmental phase,
e.g., dependency confTifef ' or decBpal conflict. Figure 6'-T oti&ies ite presentation of these
^pifl^an^p^&ls in the {iatient's Ufe as they fit into the psychiatric r^^^
11 11 It 1 11
1
i
IIU
Birth Childhoixl School Work Social/Sexual
Latest
Episode
Re-enactment
with
Therapist
Gradual
Resolution
Past History
Present Illness Mental StaQjS ^Tfieraov"^
Parapiphrt 8i3" "^i^^ipfS^'-i Paragraphs^ >
Figure 6-1. I^esentation of significant points in the patient's life in the peyehiatiic i»poi* Miiiitt.
U.S. Naval Fli^t Surgeon's Manual
Tfi<' behavior for which a patient is referred may not always be related to his core conflict,
and occasionally a patient may be seen with significant conflicts from more than one stage of
development. In such cases, the Flight Surgeon should strive to pinpoint either the conflict that
i.* I -arliest, or the one which is most prominent in the present illness.
Appendix 6-A presents an outline for psychiatric reports. Paragraph one should contain
idi'iitifying information and a list or description of the symptoms and signs that led to the
patient's referral.
Paragraph two, in acjjordanee with the PROMS System (Problem Oriented Medical
Information System) of Lawrence Weed should be an outline of the patient's ev&ryAay
world - where he lives, with whom, where he works, major iUnesses other than psyehiateic, any
handicaps that impose special burdens on him or others, and the gist of the responsibilities that
he bears.
Paragraph three should describe the context in which the symptoms and signs arose, the
precipitating eymt. If the problem is neurotic in character, then this context or event, hy
definition, will be a fresh version of prior conflict-evoking traumas or events reaching far back
iiiltj Ihc patient's past. It will have special meaning for him where it would not for others of a
diflVrent make-up and life history. Because of this and the anxiety that will naturally be
associated with such events, it will often be rather difficult to uncover the precise constellation
of I'vents to which the patient is reacting. The patient may be only vaguely aware of what is
up««tting him and will unconsciously attempt to avoid exploring fm it because of the intense
iliivioty tliat it ^n provoke. It may take very perceptive and tactful questioning to elucidate the
firliiiil context or to extract it from the apparent one. Often it may come to light only through
tlie process of analyzing and removing defenses that is psychotherapy.
, Oh the other hand, if the problem is real, rather than neurotic, the context will be quite
apparent and Will be such that the average person could be expected to react to it with
psychopathology - symptoms and signs. The diagnosis will then be one of the adjustment
reactions.
\\ liat ihe third paragraph should not consist of is simply a more exhaustive description of
llic s\ njptoms and signs (as might be appropriate in general medicine) with no mention of the
i'(Wlf*#i. This is one of the most common errors of the non-p^eluatiieally oriented examiner.
Thert' is no point in reiterating what is already well-known to the referring source while missing
the precipitating context and its significance.
6-8
Psychiatry
Paragraph four is a description of the patient, the somebody, as revealed by past history
ifrom a psychological vantage point up to the moment of, but not including, the precipitating
event. For the iseader's' benefit, it ;sh©flld'*6pte wfttefttf-sffliMttafy'.S^^
primary pattern of defense^ be it iJhaisaoteEologic (bdtewor) dis*#8Urofe
preparet tte ireafer for the sort of history that wiU be efeitowtated in the paragraph and for the
diagnosis that will be established at the very end of the report.) It should outline four or more
episodes in the patient's life that will highlight his principal core conflict, that is, what
psychosocial phase of development he has failed to negotiate, his predominant mode of coping
with it — his defenses, and how they may e®atjiltet@vfe}f#iifiio|ab^^ (»B«iae#Kl|ftiiil»al«!|ft^
fgnHlfj;^ Ijl^l^ ll^pltj|iitoi<yi#wfp^i#^ vaiTjiinig mi^mA diffei!©nt«t*tafs*if MlUfej
ffti^ii^8mple,,^biJLclh0Q^^4Mtamttt%;&iB9o^ communit)' , and ofiMpaJl^n. Typically, they will
lll^llior versions of the present pJf^M^ .#U«liW&.Ql# the latest re-enactment of the patient's
coie conflict.
There are factors in the personality other than psychodynamic and soiM
to in©ntiimiHi»i|ftfetet6fl#*ual iE!ni«hiSsn«fe Itoptem5|^t #gjpr©pieii!d by Thomas and
Chess (1977). An historical assessment in terms of their nine variables - activity, rhythmicity,
approach - withdrawal, adaptability, threshold of response, intensity of emotion, quality of
mood, distractibility, and persistence and attention span - may be very revealing and
enlightening relative to the patient's presenting problem. • "i'5' '"I
Paragraph 5, the Mentds^atuis ExaBtinatt«j shWi'flii^
current cross section of the patient's life. It should reflect how he relates to the Flight Surgeon
in the interview and how the Flight Surgeon thinks he would relate, at that same moment, to
significant others in his life outside the interview. It should be organized in such a way as to
reflect what it is to be a human being. • • • '^i" •
•>i|i*is< •• ' < • ••' •
As humans, we have a WGi*M, a world of people and things and ourseltes. We are
simultaneously open tft^flndwilff ending against various aspects of this world; Being in a
relationship characterizes us, no matter how open or defended it may be. Whatever we are aware
of, we have feelings about - our affect — and are drawn, impelled, or repelled with varying
degrees of intensity. Whatever we are aware of and have feelings about, we want to become
involved with - ,*o tflwl^j t0llwdte4o^nSi,J© Wi^eB^itD jSontrolj to love, to hate, or simply, to
disregard. We aecompbsh thte throu^ ithe instrumentality <rf o»r brain and body with its
peculiar talents, temperanient, intelligence, and seiaiality.
( )
69
U.S. Naval Flight Surgeon's Manual
Therefore, the Mental Status Examination assesses not only the patient's organic intactness
(many non-psychiatrically oriented physicians end it right there), hut e(jually, or more
im^0!tmMf fi'Om the psychiatrioi sfeiiidpoint, hii Jtiiietiond^ w emotibnal intactness and
psrtfintMj The most natural breakdown of meMtaL.^atos, therefore, is first of all into
psychological vs. organic funetioning. Then, there k a brdakdwBi Of the psychological
functioning into the natural categories of openness as assets vs. defenses, affect, and
relationships with self and others (as reflected in thought content and interaction with the
examiner). If the Flight Surgeon commits these three latter items to memory and assesses the
patient m these terms, he cannot fail to prodtJtee a credible and creditable psychological portion
of the mental status examination, and he will have covered every conceivable item of
psychological functioning. Th^es h (XHB ftttthei- baafcdown to be kept in mind and that is
defenses. Defenses, in this conception, include not only mechanisms of defense, but all forms of
psychopathoiogy, such as personality disorders, drug abuse, neuroses, and (functional)
psychoses. They are all defenses against anxiety even if some, e.g., the psychophysiologic
disorders, ai% ^somatic expresdons of it as wdl. "13iese three breakdowns will help the examiner
to organize, in his mind and in his report, mjwad possibilities of psyehological functioning. The
patient's general appearance (this should be the opening item) is added to this and then the
description of the psychological functioning is followed with the organic functioning in terms of
sensorium (orientation and memory) and intellect. Finally, the Flight Surgeon's judgement,
insight, md his assessment of the patient's potential for therapy are discussed. These latter stand
out separately because they partake of both psychological and organic functioning and
intactness. The results of any psychological tests (Appendix 6-B) complete the picture of the
patient's functioning in the here-and-now, the current moment in his life.
Paragiaph six is a capsule summary of the patient and his difficulty. It comprises three
elements - his personality pattern (be it healthy, neurotic, or characterologically impaired), the
context, and the symptoms and signs. This is the gist of paragraphs one, three, and four. From
these and paragraph five, comes the diagnosis in paragraph seven.
■ t .-,
The eighth and final paragraph contains the recommendations for thterapy and/or
disposition that are a natural outcome of the precediag data, ' '
When structured in this ihaainer, the report strikes the reader with coherence and
persuasiveness. One part relates perfectly and logically with' aii^ther, and Hie clagnosis falls
naturally into place. The patient comes across as a comj^rehensible human being and the reader
will believe what is said about him and will do willi him what is advised.
6-10
Psychiatry
The Evaluation of Candidates •!■!!• iii. -
Future performance is best predicted by past performance; only failure can be predicted
with any acceptable degree of reliabibty. Therefore, when tliere is evidence of psycliopathology
in a candidate which has significantly interfered with his adjustment in the past and which has
not *lj«il resolved, the Flight Surgeon may iiitiv^mmm rejecting him either dn iJie;b«s«Edfai@lE:
of aeronautical adafftiaMKty W IfJ ap^tmally.e^^ a.diagpqsis. In consideriijgi whelfaifei^
establish a diagnosis, however, lie shjauld,lcd^ ;Si Blind that tK* candidate has not come tabe
penalized by having a diagnosis of occupational maladjustment tagged to him that may follow
him for the rest of his life, lie wants only to fly and see]s^ji|i (jpjfldpli,^^^ to
give the label of "not aeronautically adapted."
The best approach for evsduation is the use of the traditional format for a psychiatric
evaluation, ti^iig,ii^ if^ie chief jDflWplfliilt the candid##'fea|>|!^^pt.%ns..fli^t training
conscious aia^^^ Uijconscious reasons for doing so as the cont^|,{^jthough it is nearly impossible
to predict success in military aviation, still, the Flight Surgeon can look for evidence of early
interest in flying, such as building model airplanes, frequenting airfields to watch the planes take
off and land, and identification with parents' interest in aviation. Further, there should be
evidence of maturing in motivation froin the roniariiicism of the boyhood years to the practical
ratploration of alternatives of the postadolescent yeajs. Eetnhwdt (1970) hai|i|^a|s^4j|t^.j^|fi^
the outstanding jet naval aviator is an extroyaflf^? first-born, problem solver. He also observed,
culminating his remarks on selection, that any normal, red-blooded American boy can learn to
fly (U.S. Naval Flight Surgeon's Manual^ 1968). Some, however, may lack the ^basjc
temperament for military flying.
The Evaluation of Students , ■ . : . , '
When students experience problems in learning to fly, the Flight Surgeon first ascertains the
particular aspect Of t*ailiafieo5Etfrcratil%theiaai £Mi|h»'j^ withins.^i'wfeflt' js/i^iWiel for
tiaem — the context. Is it tl^tUttd dimension of space, a new, more complex aircraft, the idea
or feeling of being number one in the plane, of being solely responsible, a real or neurotic
reaction to the instructor, or perhaps stresses external to flying? Then, from the past history, he
must uncover what there is about the student that renders him pathologically susceptible to ijte
particular stress. Is this a compulsive student overwfeeiaieiel b^#io tapid'a pB^entafca ofiSBe*r
material; is an hysterieal.indMdual reacting to unconsciously pereeived^danger with a converMom
symptom or careles&,-^itef flyin^i-OfHs this a characterolo^effly-^ttspl student:4^bMBg t®1real
and abnormally intense stresses in or out of aviation?
U.S. Naval FiigKt Surgeon's Manual
EviAlliltiOn of Designated Fli^t Personnel
The seasoned professional typically may be facing a transition from a staff assignment or a
school to a new, unfamiliar, more complex, and powerful aircraft, reacting to an incident or
accident, or, just as likely, experiencing problems external to flying. In other words, here the
Stress^ 'Mtete llfcdy to he real smd i^tensey-mthet thaa;MtrapsycMcj1fte'Mig Surgeon ia more
likely to be dfcalnlg with an adjua^#nt reaotiotl rathet»tb$n a neurotic process.
Dispositioft depends on motivation and safety. A patient suffering a conversion symptom
usually cannot fly safely and must be grounded, at least temporarily until therapy can resolve
his symptom. One with a psychophysiologic disorder that is minor, however, may well fly
safely, be strongly motivated to continue flying, and may be peWnitted to do so, with or
wltK,0^ tftfef Jlpiy. Ill most other caseis, ?yteptdttis must be resolved b^oire flying eaii be resumed,
arid UifeVfe sHottld be Ktifle likelihood bf titeir redurrence. In doubtful instances the pa:tient's case
sKould'he liifbu^t bfefote a E^bcH of * Sp#5Ml feit'cl FB|kf lilfg#<ia^ for disposition.
Treatment Modalities
Brief Psycholftfeafaijiy
Everyone carries recotifed in his tti&id dffecliviefy colored experiences and fantasies that
shape Mf map of reiiJify (and behavior) and may lead him to misperceive his present situation
and to respond inappropriately. Painful feelings and symptoms may be the result. The therapist
attempts to help the patient recover these latent memories and fantasies with their associated
feelings so that he can reassess and interpret accurately what is going on now, relinquish
symptoms and painful feeUngs, make realistic deciaons, and take appropriate aCtiittn.
Brief psychotherapy m erisis and presen^problem oriented. In its ef f ort» therefore, to relieve
painful feelings, it delves only into that aspect of the past that directiy pertains to the
presenting problem. It takes advantage of the fact that the patient's greatest motivation for
change occurs in times of crisis and that the solution of one problem may lead to beneficial
alterations inthetotd persoiiaHty With considerabMiteaiarati^^^^^ mMetuise of techniques as
muffle fflid practieal as providing a good nl^tV sleep to as esoteric as dealing^with transference
if the patient uses it as a resistance to therapy. The crucial element in psychotherapy, however,
is the working or therapeutic alliance — one adult working with another within the mature
aspects of their personalities to help the patient shed pathological defenses and resume
responsibility for his life and future (Greenson, 1967; Zetzel, 1956). A balance is struck
between a purely supportive approach and superficial uncovering of a counseling or
psychoanalytically oriented nature.
6.12
Psychiatry
Since identification witii the therapist is fostered or at least not discouraged as one nieati> m
maturing and improving defenses, it follows that the therapist must be a inod< l <>i
incorruptibility. Further, he should be the vehicle for "ejwKteetiv© sinii^oiied enpierar-nfi*-
(Alexander & French, 1976), with responses different from the prgsunipd pathological otn> ui
the patient's parents or parental surrogates.
The number of sessions is set from the beginning at ten or twelve to proiiiolc I In
exploration of dependency conflicts and separation anxieties, apparently one of tlic prevalrm
problems of our age, and one that is particularly exacerbated in the military and by the sdlitar)
nature of some aspects of military flying.
71$e Method. The following method statements are taken 'lli^^.l^ljfpi
1. The therapi^ is much more active than in traditional psych^l^riEipy,^ and jdnerapy h\n><
to face.
2. The diagnostic process as described in the section on psychiatric evaluation t-
undertaken with assessment of ego functions and defenses and suicidal or homicidal x\4>,.
3* The fbcus is on the main conflict in the present, the context of the symptoms. 11
current life crisis, the emotionally hazardous, sitnaHoni and the.|it£|iit% perceptum • I
the feared stirhulus (Mitchell, 1976). j v . ,
4. The working alliance is actively fostered via the rationali mi|jbii|;«gii>|,^V^.tlig.posjlKi'
transference and the feeling of hope is encouraged.
5. Negative transference is promptly interpreted.
6. Time limits are set early to promote an active working alliance and to set the s-b^ii-
decisively for the activation and exploration of dependency conflicts and sepiaration
anxieties.
7. Some of the principal treatment elements are:
a. the reduction of anxiety by
1) history taking
2) medication and rest (may even include brief hospitalization)
3) the showing of interest and respect for the patient's worth as a human bcinj;
b. ventilation — This implies listening on the part of the therapist. The paii' -n
viQiluntfM^ i^bi^B'^MiBMI^iireiMly- to ^whatj haters as he ventilates^ ^his is a f < trtr
of self-desensitization to the feared stimulus and is ameliorative, if not curati\<'. I li-
degree to which the patient ventilates varies directly with his confidence and trut^l r
, :^£! therapist's acceptance (Wachtel, 1976).
c. ^mM£l^:0^k!^i'*i'W^is m^tsd (if the patient is anxious^depr^ed, oMdnfusi*d. 1 1 ' '
.--cannc»t:timk.iit@8jly)^by 'j.n'u.r
1) defining the problem — the context of symptoms
6-13
U.S. Naval Flight Surgeon's Manual
,, ,,; a) space
b) lack of fusion with the aircraft
.- ; / ■ '©I ' beteg in eontrol
' jl) •Statefr-imtructor relationship
e) problems external to flying
2) reviewing gojds — reminding the patient why he chose to fly
3) reminding the patient that a modicum of saHiiky is iioimial under his
circumstances, that he is hke everyone else
d. emphasis of assets, especially the ability to solve the newly -defined problem.
Initiative is given to the patient.
e. the clear definition of the presenting problem. Goals for the therapy relative to the
fj -«^^^VCT ^biS^e, the elicitafioii -horn the patltenl of a fitta contract for a specific
behavioral change, a change highly desired by the patient. This has the added
advantage of simultaneously brii^ing his defenses and iidiibitions into the sharpest
possible foGxm for therapeutie iscrutiny and r^Qlution<
g. agreem^t ' between the patient and i&k&spM on what the signs wiU be that the
contract has been fiilfilledj, so that they will dearly know when it takes place
(HoUoway, 1977)
h. repair of ego and super-ego lacunae, partially via identification with the therapist
i. loosening of rigid or pathological defenses. This is fostered by confronting and
interpretation.
j. encouragement and strengthening of healthy defenses
k. encouragement of the patient to meet his responsibiUties and, where possible, to
face what he fears in manageable increments
1. emphasis of his success, no matter how small, for positive f eedbacl^
m. interpretation of genetic determinants. This meaijs exploration of the patient's past,
but only as it relates to the pre^nt problem and only as the patient is able to handle it.
n. occurrence of insights with opportunities for the patient to change, redecide old
issues, relinquish archaic ties, make new decisions, and take initiatives. Interpreta-
tion and insight are therapist and patient fcinna ol. I^admfidv fcared^Mimulus
exposure and desensitization in psychotherapeutic tirm&that leSd tOkameUoration or
cure (Wachtd, 1976).
o. environmental manipulation. This can range from a night's rest, to rescheduUng a
flight, to changing instructors, to a transfer, to the extreme of hospitalization.
Mimipulati^lt' is to be used sparingly because it is infantalizing, taking over the
running of the patient's life. 'It is better to encourage him to make 'necessary changes
himself.
6-14
Psychiatry
p. finally, termination as agreed upon, or earUer, if the patient is able to take over and
solve his problem. The twrniliaiioil interview skoxkdinelude interpretation of any
anger at rejection and an open invitation to return,
8. If referral or hospitalization is indicated, the therapist should explain thoroughly what
the patient can expect on admission and be prepared to deal with the anger of rejection.
Talk of more lengthy treatment should be deferred until the therapist has accomplished
wtiaf 4e "isife'yi&^^rfii^^ efforts i^uwwtJte'a WM^teblnf^ )Wrti>m«>jiO*abi&^
TpaiieMm^^y^sAf^^'^i^i^i is going Ito *0!illitte«ill%<Jr e)m, >
In attempting therapy, there are two things which should be kept in mind:
1. There are three phases to it:
a. The opening phase — the patient attempts to develop trust in the therapist, and for a
tifflje^ 'tecoin^> syinptoril'-fiEte :a»'h& ftadts igSBi^^ um gratify his
infantile needs. This can lead a therapist to conclude that he has acconvpHshed a
miraculously speedy cure.
b. The middle phase — symptoms return and work begins
c. The closing phase — dependency conflicts and separation anxieties come to the fore
as the patient realizes that termination is imminent. Symptoms may temporarily
ei^pt agsd^jii.f defense against having to leave the therapist. There may also be an
unconscious anger at being rejected, and the defense and anger must be interpreted.
2. Countertransference - the irrational and infantile feelings generated in the therapist by
the patient that come from the unresolved conflicts in the therapist's past can be used to
advantage or be detrimental to the therapy. This can alert the therapist to the fact that
the patimt is dealing with neurotic conflicts and feelings by hooking the therapist, so to
speak, into neurotic interaction to gratify infantile needs, or the therapist may succumb,
wittingly or otherwise, and the therapy will be sabotaged. If the therapist finds himself
unable to resist the latter outcome, the patient must be referred to someone else. Eew
therapists, perhaps, can deal with all types of patients, particularly without psycho-
, , therapy themselves to remove as many of their blindspots as possible, as a prelude to
becoming effective psychotherapists.
Note-taking during sessions is perfectly appropriate for the initial evaluation, but in therapy
it is to be avoided. After the therapy session is over, the therapist may find it helpful to reduce
his thoughts to the format of the SOAP formula of the PROMIS system. The themes of the
hour can tie aimni^a tiiid^' any changes W W '^ma^^ '^^^ m'W
mini-mental stdtus), for example, alterations ui defenses or deVelopitieftt' Bf 'ik§pfe( Can h6
recorded under Objective, as well as any laboratory findings, current tests, additional outside
information, or the results of consultations with other specialists; thoughts about what is going
on, or a major shift in hypothesis, can be briefly put down under Assessment, and a plan for the
next hour under Plan. This method will keep the therapist from straying, wandering, and
6-15
U.S. Naval Fli^t Surgeon's Manual
wasting |)reGious time., a thing all too easy to do in such a potentially nebulous undertaking as
psychotherapy.
Marital Therapy
Marital therapy is not individual therapy with two people; there are unique, complex
dyiiaMiies involved in the marital relationship that extend beyond the boundaries of the marital
partners. IfoweviBr (jomplex this relationship, it is stiU possible to unravel and understand
enough of it to effect a change in a disturbed marriage. The responsibility for change rests with
the husband and wife, whether it be to make the change within the marriage or to change by
separation. There even may be the decision not to change but to keep the status quo as the least
painful of the three choices. Any one of the three decisions — stay married and change, divorce,
make no change — is legitimate, but it should be made on the basis of information derived from
the marital therapy process.
The marital therapy process is based o.i two concepts germane to any interpersonal
relationship — needs and communication. If needs complementary to the marriage, conscious or
unconscious, are met, then the relationship remains stable. If these needs are not met, then
communioiitlion ttecqsSiary to estabHsh m awareness and a means Tvhereby they will be met.
It is helpful to hfve fefe couple enumerate their needs both as individuals and as partners in a
marriage. This serves two purposes: one, to bring into mutual awareness the expectations each
holds for himself and the partner which then can develop into a quid pro quo arrangement
underlying successful marriage, and, two, to introduce fundamental communication usually
lacking in problem marriages. Communication is not limited to mere verbal exchange, but it
includes connotation and nonverbal cues as well.
The Fhght Surgeon will probably not have time to do long-terra marital therapy; what he
can offer, wilt be short-term, supportive counseling. Referral sources such as chaplains, legal
officers, local ministers, other medical and psychological specialists, and even books on the
subject are invaluable in extending his limitations for comprehensive treatment. If long-term
therapy is indicated, the Flight Sui^on should baye ayi^able a list of appropriate referral
sources (psychiatrists, psychologists, marriage counselors) via his own efforts and personal
knowledge of their quaUtications.
Because of the absence of the spouse, deployments and unaccompanied-tour duty stations
severely limit the effe<;tiv^i|ess of marital therapy; supportive therapy and referral sources
become essential in treating one partner. For the husband, ihe Flight burgeon may be limited to
treating the symptoms, depression, anxiety, etc., and simply being available as someone for him
6-16
to talk to. For the wife, the Flight Surgeon wUl be limited to his list of referral sources and
making appropriate recommendations from that. The kinds of problems encountered may range
from newly weds' initial adjustment arguments to complex sexual dysfunction involving other
psyehiait^gjpl^MMMin^td idle ■>"..-.■■ .rv .-fu-fu tr»»n
• The Flight Surgeon's goals and values underlying miudM therapy should allow for divorce ot
separation as a realistic "treatment" alternative and prepare him to assist in that task. If divorce
does happen, his efforts are not necessarily in vain, as explained by Sadock (1976, p. 502):
Marital therapy does not ensure the maintenance of any marriage.
I, Rather, in certain instances it may serve to clarify for the partners that
they are, for a variety of reasons, in a nonviable union that should be
dissolved. As difficult 'as such a decision is to make, there is some
gratification in the knowledge that every attempt to save the marriage
was made. The partners not ordy separate with less feeUng of guilt but
provide tl^te|i^^«^KMl>'€{ffii^ijasii^
suf ficien^f Jf-^lf tQ,|»fe!Sr^iit a iip|Ufej|!^ipiii^
i't-e 111 til.''
Theories of Behavior Therapy
All behavior therapies rest on the assumption that most human behavior, normal and
abnymal, is learned. As such, behavior treatment involves the «pplle«feB}<jfilll«^^
to modify or eliminate maladaptive behavior and to acquire behaviors considered to be adaptive.
Respondent (Qassical) Conditioning. If a neutral stimulus becomes temporally associated
with another stimulus which naturally evokes an unlearned response (reflex), and the two are
paired repeatedly, the neutral stimulus alone wiU then evoke the unlearned response (reflex).
fhe-f^Airtf? n@ii»it' i#'^ffl©# ttedfe^aiil t' tJoiiiMatia^-^iijrt ^^^m
cdnditi0nM'»''^pftie. 'iTMs-'pAifipfe *i«i|fild'%- a T<^ll6" «Wtetf 'ei '
Av1^V@^i6lkiittit!i£$iiil'il^tM^ desensitization.
Operant Conditioning. When a response is made to a given stimulus which results in
something happening that increases the probability that the stimulus-response connection will
be made again (reinforcing), operant conditioning has taken place.
TMi 'lUtMblg principle finds appli(^tip$'*iii thi treatment of many psychopathological
eonditions ranging from schizophrenia to conduct disorders in children, and it is also employed
in assertiveness training.
U.S. Naval FU^t Surgeon's Mamul
Social Learning. Bandura, Grusec, and Menlove (1966), Bandura, Ross, and Ross (1961),
and Bandura and Walters (1963) reported studies which demonstrated that subjects could learn
quite complex behaviors simply by seeing and hearing other people model these behaviors.
Hiere are many variables that influence wksi md how mucJlis leaS&ed'through modeling, such
as the observer's sex and age in relation to the model. Group therapies, including Alcoholics
Anonymous, play therapy, and marital therapy, are some settings in which social learning
principles are used in behavioral treatment.
Techniques of Behavior Therapy
Relaxation Therapy and Systematic Desensitization. Anxiety related to specific situations is
effectively treated via relaxation with desensitization, or relaxation therapy alone can be very
effective in treating anxiety symptoms in which no specific context can be identified.
Respondent e«^fiditioning principles apply in these techniques. Basically, the following
procedure is used in teaching the patient relaxation "exercises: " (1) Sit or lie comfortably in a
chair or sofa in a quiet, semi-darkened room. (2) Tense and relas individual muscle groups
(forehead, face, neck, shoulders, arms, back, stomach, thighs, calves). Tense each muscle group
for about three seconds before relaxing and going on to the next. (3) Focus and concentrate on
rhythmic breathing, deeper muscle relaxation, and the imagination of a pleasant, relaxing
experience. (4) Lie totally rdaxed for approximately one minute, ten awaken by counting
backwards from five to one.
This procedure, discussed in more detail by Wolpe and Lazarus (1966), is practiced by the
patient twice a day for approximately a week, or until he is able to relax himself at wUI using
the technique. The application of relaxation in systematic desensitization begins with the
patient constructing an "imxiety hierachy," a graded list of situations or events which evoke
anxiety. The patient then imagines each item on the hierachy while in a deeply relaxed state. In
particularly difficult cases, drug relaxants or hypnotics may be used in conjunction with the
relaxation procedure described above. The patient progresses from least to most anxiety-
arousing events as each evokes absolutely no anxiety when vividly imagined by the patient.
In vivo desensitization is also practiced by the patient, if practicable, e.g., sitting in the cockpit
of an aircraft for flight anxiety.
Other Techniques. Modeling and role-playing are general methods of behavior therapy which
pimply involve the interaction of patient and therapist and the patient and important-others as
models for desired behavior acquisition. The selected behavior is observed, then practiced, until
skill is attained and anxiety is absent. Assertive training, fixed-role therapy (Kelly, 1955), and a
wide variety of group and play therapies employ modehng and role-playing.
618
Psyehiatry
Aversive conditioning is used in the treatment of alcokolism by developing an av^ion
towards alcohol through the ingestion of Antabuse. Narcotic and tobacoo addiction are treafed
in the same manner by different dru^ as the aversive stimulus.
Broad-spectrum behavior therapy (Lazarus, 1971) or, more recentiy, multimodal therapy
(Laxarus, 1973) is a variety of techniques employing all that is available in the patient's and
therapist's armamentarium. Traditional techniques, including interpretation, reflection, free-
associatiOUv isupport, and eathareis, in addition to coaw^tsiMd behavioral methods, are
espoused. The acronyn BASIC ID denotes the seven interactive modalities involved in the
multimodal psychotherapeutic process: behavior, affect, sensation, imagery, cognition, inter-
personal relationships, and drugs. This comprehensive treatment "calls for the correction of
irrational beliefs, deviant behavior, unpleasant feelings, intendve images, stressful relation^ps,
negative sensationsy and possible biochemical imbalance" (Lazarus, 1973, p. 407).
Chemotherapy
More and iaore of the organic substrate of emotional illness is being discovered daily. This
does not mean, however, that the psychological counts for naught. They must both be dealt
with, or the patient wiU remain partially crippled. He may be so confused, upset, or depressed
that he cannot think about his problems until some physical or chemical stability is restored.
On the other hand, to restore hjM cheWlicaUy ani Ms |ft^eT|(iE^^
their recurrence.
Psychoses. The most popular, current, organic explanation of schizophrenia is that an excess
of dopamine is produced by a deficit of dopamine jS-hydroxylase, the enzyme that normally
converts it to norepinephrine in noradrenergic neurons. (GABA may also be involved in this
system as an enzyme in a homeostatic loop). This may also explain the depression and apathy
that often accompany the disturbance of thought processes. It is of particular further interest to
note that, according to a review of recent literature (Ban, 1977), alcohol consumption leads to
an increased synthesis of these same cateholamines, leading to the possibility of aggravating
schizophrenia; it would also relieve depression temporarily. He further pointed to studies that
suggested that Antabuse inhibits dopamine (3-hydroxylase, thereby mimicking or aggravating
schizophrenia.
AirtttpiBydhotic drugs, phenothiazines, butyrophenones, mi thioxanthenes, have many
properties, but they all share one, the ability to block dopamine receptors. This same property
is responsible for two other effects, extrapyramidal symptoms and tardive dyskinesia.
Fortunately, the anticholinergic drugs, Cogentin, Artane, and Kemadrin, can partially overcome
this block by blocking the reuptake of the catecholamines and serotdnih. Those phenothiazines
6-19
U.S. Naval Fli^t Surgeon's Manual
with the most prominent anticholinergic properties, e.g., Melkril, are, for this reason, least
likely to produce extrapyramidal symptoms. Unfortunately, there is no treatment for tardive
dyskinesia, thought to be the result of a progressive hypersensitivity of the blocked dopamine
receptors to the presence of even small amounts of dopamine.
At any rate, the antipsychotics are the treatment of choice for psychotic reactions, even
those of toxic or infectious etiology. It is wise to become well-ac<piainted with one or two
members of this class, perhaps one that is sedative and one that is not. 'Hieir sedative effect is
immediate; their antipsychotic effect is cumulative and may be delayed from hours to days.
Therefore, once the patient is under control, the total daily dose may be given at bedtime to
take advantage of the sedative effect at night and not hinder the patient during the day.
If hypotension occurs and threatens the patient, levophed or neosynephrine may be given,
but epinephrine like compounds may potentiate the hypotension because phenothiazines are
os-adrenergic blockers.
If extrapyramidal symptoms incapacitate the patient, Cogentin, 1 mg, may be given I.V. or
I.M. STAT and then p.o. from Y^to 1 mgb.i.d. Benadryl, 25 to 50 mgm, I.V., or short-acting
barbiturates may be used if Gogetin is not available. Since these dru^ act, however, by blocking
the reuptake of the catecholamines, they may a^avate the psychosis and require an increase in
antipsychotic medication. Therefore, the least amount necessary should be used, and the patient
should be titrated off of them when possible. It may be sufficient from the outset simply to
lower the antipsychotic medication.
Manic-depressive illness, manic or circular types, is thou^t to be due to an exceiss of
norepinephrine. Particularly when the illness is familial and bipolar, the disease responds to
Lithium, but it takes several days, four or more, for an effective blood level to be reached. In
the interim, Haldol or Thorazine are the dru^ of choice, 2 to 5 rag of Haldol or 50 to 100 mg
of Thorazine I.M. as starting doses.
Lilhium is thou^t to act by accelerating the catabolkm of norepinephrine, iidiibiting the
release of norepinephrine and serotonin, and stimulating the norepinephriiie reuptake process.
Further, it appears to stabihze intracellular sodium (thought to be increased in depressions) via
the sodium-potassium-adenosine triphosphatase system, which is also magnesium dependent,
and is possibly involved in corticosteroid stabilization. More Lithium is required in the early
agitated phase, as much as 1500 to 2000 mgper day, hut the requirement quickly falls with the
patient's improvement to about 600 to IZ&O m^ per for a blood level that ranges from
0.8 to 1.5 mEq/L. Hydration must be carefuUy maintained. Any febrile illness with diaphoresis
6-20
Psychiatry
or loss of fluid through diarrhea may result in toidtl^f ifrhieh wil oeour rapidly iEi>0ve
LSmEij/L, and death may supervene at 3.® mEq/L. Signs £md symptoms are those of the
central nervous, gastrointestinal, and cardiac systems. Lithium must be promptly discontinued
until proper hydration is regained. The level will fall quickly. Lithium cannot safely be
prescribed without the ready availability of a competent laboratory.
Depressions. Depression is thou^t to be a result of a depression of serotonin level with a
choliner^ie-noradrenergiC' imbalance. The norepinephrine level may be^awfy, but symptoms will
not supervene unless the serotonin level is low. Serotonin deficiency seems to be associated with
insomnia; acetylcholine increase or norepinephrine decrease is associated with psychomotor
retardation, or if norepinephrine is in excess, agitation. ^^.
Antidepressants, particularly the tricyclics, Tofranil, Elavil, Vivactil, or Sinequan, are the
drugs of choice, as they act to increase the catecholamines and serotonin by blocking their
reuptake, and they have some anticholinergic effect. The dosage is the same for all - 25 to
50 mg t.i.d. to q.i.d., p.o., with a maximum of 300 mg per day. Tofranil is the drug of choice in
retarded depressions; Vivactil may be more stimulating, but it has been associatCid wi^h the
onset of seizures. Elavil is the drug of choice in agitated or anxious depressions, and Sinequan is
recommended for the elderly or those with suspected cardiac disease. Dosage for the elderly
should be reduced and started with as little as 10 mg b.i.d. The sedative effect as with the
antipsychotics is immediate; the antidepressant effect, cumulative and delayed. For this reason,
aU the medication may be given at bedtime, if desired, to take advantage of the sedative effect.
The medication shouM be continued for at least three weeks, for improvement will often take
that long to become evident. The risk of suieade iase»as the patient becomes more enerpfeJxs
must be ohi^rved closely until improvement is sustained, and^vfee iseMERes fonftioriing.
Occasionally, electro-shock therapy must be resorted to as an emergency measure against the
danger of suicide. When the patient does begin eating and sleeping normally, and his energy
seems restored, the antidepressant dosage should be reduced to a maintenance level for a
minimum of three months. This level will be 25 to SO.mg p.o. per day. Thjenj it sl}#1Uld be
tapered off completely mm a three-week period. If symptoms return, then another period of
several months of maintenance dosage is in order. Authors aver that the more intractable and
recurring the initial symptoms, the longer the maintenance period must Jjf .. , ... . . ,
I
If the depression is mild, but discomforting, Valium may be tried first as a simpler measure.
Most authorities agree that it has a mild, though unexplained, antidepressant effect.
Anxiety. The physiology of anxiety is just beginning to be unraveled. Regardless, there are
many effective minor tranqililizers; imfortuAately, practically all are potentially addictive.
Therefore, they should otdy be short-term adjuncts to other forms of therapy.
6^21
U.S. Naval Fli^t Surgeon's Manual
VaLium^ for mmy ffsasons,. appesffs to be the drug oL^haieei. Two of the most important are
its wide margin of safety and its ability to relax striated muscle. Dose ranges from 2.5 to
10 mg t.i.d. to q.i.d. p.o. It is also becoming the drug of choice for the treatment of withdrawal
from alcohol and other sedative/ataractic drugs. Recent, early reports suggest that it exerts its
atttian:!£iety effect by suppressing serotonin by fflimicjdng GABA in the midbrain raphe cells and
its muscle relaxant effect by mimicking ^ycine in the spinal cord (Benzodiazepines, 1977).
Insomnia. Insomnia is a ubiquitous complaint, especially in psychiatric patients. Rather than
automatically prescribing a sedative, however, the physician should investigate for the many
causes of insomnia and, where possible, treat the basic cause. Simple anxiety is probably the
most common cause, depression next. Antidepressants rather than sedatives may be the
treatment of choice. If a sedative is appropriate, however, Dalmane is the drug of choice in
doses of 15 to 30 mg p.o. HS., It is the only^ isedativfe that does not result in REM rebound and is
effective for more than a few nights, that is, it does not seem to provoke tolerance. Still, it
seems wise not to prescribe it for more than a few nights, while attacking the basic problem
through other avenues. Dalmane may be very effective in deahng with the acute insomnia that
may accompany grief reactions.
Fatmt Pemmiity md the flmxbo EffJtct, H 'significant portibn 6f the effect of any
medication is a function of the physician's relationship with the patient and the phenomenon of
transference, the patient's and the therapist's (Dewald, 1971). On the negative side, the patient
may have an unconscious need to defeat the therapist; as a matter of fact, to recover may mean
facing some anxiety, giving up a secondary gain, or both. If the medication fails to work and
produces unpleasant side effects in the b^gain, partieularly if the patient was not forewarned of
the conmon ones in simple terms in advance, a damaging effect on rapport and morale is a
Ukely 0uteoine.
It is often useful to take into account the personahty and traits of the patient when
prescribing. Elaborate detad, perhaps even a lafaior ritSial, may be helpful for the obsessive-
compul^vg parent; convetsdy, a minimum of detail, leaving as much control to the patient as
possible, may be approprikte for the passive-aggresidVe, md firm insistence may be indicated in
dealing with the patient who must deny dependency and who, for that reason, normally shies
away from all medication.
Hazards of Drug Therapy in Fsychiairh Treatment. One must think twice before prescribing
medication for the dcohoECa the compulsive overeater, and the overtly dependent patient. In a
depr^sS^d patient, suicidal risk; itiMJtst. be balanced against the need for trust hi a therapeutic
relationship. If the patient depa^s from the regimen prescribed (for defensive reasons), gentle
6-22
confrontation and interpretation are indicated. Physiological or side effects may be sufficient to
result hi increased, rather than decreased, anxiety and may be misinterpreted by the physician,
leading him to overprescribe or add other medication compounding the problem and seriously
eroding trust. Lastly, the therapist must avoid using drugs as a substitute for psychotherapy
rather llian as an adjunct. The use of medication tends to focus the patient's attention on reality
ifiBjues jpS may fooiP uneonscious factors and feelings to the detriment of real and lasting
improv^mt^ i
Overdose. The following general principles for the treatment of overdose or drug abuse are
taken from Chapel (1973), Greenblatt and Shader (1974), and Munoi; (1976):
1. Identification of the drug ' ,
2. Evacuation via emesis and lavage
3. Neutralization via antidote • > ■<
4. Symptomatic treatment and supportive measures. . • ' •
In overdose with psychotropic medications, the following steps should be taken:
1. Insure an adequate airway - intubation or, rarely, tracheostomy if necessary in the
comatose patient, with vital signs and turning
2. Emesis in the conscious patient - syrup of ipecac, one teaspoon for a child, two for an
adult. This may be repeated in fifteen ndnutes.
3. Gastric lavage. Do not attempt this in the comatose patient without intubation and cuff
to preclude aspiration pneumonia. Use a solution of 0.5 percent noiiO^ saline or a
solution of 1/10,000 potassium permanganate for alkaloid poisoning. Activated char-
coal, 4 to 16 cc, may also be used in solution. Continue lavage until returned solution is
dear. In the case of tricyclics, one author recommends lavage for 24 hours on the basis
that itie excretion of tricyclics occurs partly in the stomach.
4. An I.V. with five percent glucose in saline. Maintain fluid balance. One author
recommends an immediate injection of 50 cc of 50 percent glucose in saline in comatose
patients considering that hypoglycemia as a possible cause is thereby quickly iftd s&aply
treated and/or ruled out.
5. Blood and urinalysis to identify the drug, as well as a history from a reliable informant
6. Other supportive measures as may be indicated - indwelling catheter, cardiac monitor-
ing, treatment for shock, hyperpyrexia, and potential seiKQres.
''It lias dhady been IliienMied that epinephi&e'aild Mated compounds must be aydtl^dfot
the hypotension due to the aritifjiychotic MV khtidbpres&an^^ medlcatidhs'td SatoM'^al'dtoxical
further lowering of the blood pressure. Levophed or neosynephrine are the drugs of choice, one
ampule, titrated in an I.V. drip.
6.23
U.S. Naval Pli^t Surgeon's Manual
If j^datioii is teq^fted for agitation or ike danger of seizures, oral or I.V. Valium, 5 to
20 mg, appears to be the drug of choice. Where the overdOse is from amphetamine or related
compounds, the use of a phenothiazine for sedation may pr^pitate an intractable hypotensive
reaction. ■
Hie central anticholiner^e syndrome (CAS) miff be a concomitant of overdose with
antipsychotic and antidepressant drugs, as well as with the antidiolinergics prescribed tcf relieve
the pseudo-Parkinsonian symptoms induced by the antipsyehoticB (Holinger and Klawans,
1976).
The central nervous system symptoms and signs are
1. ablation
2. disorientation
3. hallucinations — visual and auditory
4. anxiety
5. purposeless movements
6. cblirium , .
7. stupor
8. coma.
The peripheral nervous system symptoms and signs are
1. flushing
2. dry mouth
3. constipation
4. mjhchiasis
5. tempcrattxire elevation
6. motor incoordination
7. tachycardia.
These symptoms and signs are all dose related. They are Mie result of a competitive
inhibition of acetylchoHne. The antidote, physostigmine, which unlike neostigmine can cross
the blood-brain barrier, destroys the enzyme anticholinesterase, , perffliJWiilg: an increasing
buildup of acetylcholine that finally overcomes the block at the teceptor sites.
Profound coma and other characteristic symptoms of the CAS syndrome may be
relieved immediately by the administration of physostigmine in doses of 1 to 4 mg as
6-24
often as indicated, usually every hour until symptoms and sigiis piewri«(reiti^f Abate. This is
usually no more than 25 hours, at most.
Combat Psychiatry
In combat and in military flying as well, the emphasis in understanding psychological
reactions is on the external stress. The symptoms and signs run the fu' gamut of the psychiatric
nomenclature, but quick recovery is the rule when the patient is removed from the stress.
Experience has shown over and over that if a combatant is treated quickly, close to his Ui^^ and
led to expect that he will return as soon as possible to his unit, results are not only v^ good,
but far superior to those obtained when a man is treated a long way from his buddies, with
some delay, and with uncertain expectations. Thus the cardinal principles of immediacy,
proximity, and expectancy were gradually evolved and proven.
During the Korean War these principles were furliier refeted (MuUin, 1964):
1. Treat as near to the unit as possible.
2. Segregate the most agitated patients until they can be adequately sedated.
3. Sedate sufficiently to reduce anxiety and insure sleep.
4. Accept the patient as a casualty, but with the attitude that his symptoms are transient
and tiiat he will recovet and go back to his unit,
5. Say or do nothing that would indicate evacuatiiiin.
6. Ventilation is encouraged; interpretation, avoided.
7. Once disposition is decided, inform the patient, avoiding argument.
8. Eeturn the patient to duty as soon as possible, often within 24 houi58.
% Evacuate patients vMi the faUo-^iig conditions m a guideline:
a. the obviously psychotic — rare » conabat
b. conversion reactions - the blind and paraplegic
c. the severely apathetic who appear emotionally depleted
d. those who show gross tremor and chronic startleability
e. the NCO and officer with impaired judgement or who may set bad examples.
Str^e and Arthur (1967). wrote about "combat fatigue" and defined it as a transient,
patholo^cal reaction in a basically healthy personahty to the severe stress of combat.
They also distinguished between genuine combat fatigue and pseuddcoittbat fatigue. Imdse
with true combat fatigue
1. ^ve a past history of healthy emotional adjustment
6-25
U.S. Naval Ili^t Surgeon's Manual
2. had performed well
3. had severe and prolonged exposure to traumatic combat
4. were, typically, junior, non-commissioned officers with a lot of responsibility,
e.g., corpsmen and squad leaders
5. were m the way zone more than six months
6. most commonly had symptoms of depression, guUt, and psychophysiologic reactions.
On the other hand, those with pseudocombat fatigue
1. gave a history of lifelong poor soeial and emotional adjustment
2. were in the war zone less than six months
9. were exposed ttiinimally to combat
4. rarely experienced guUt
5. were rarely in positions of leadership.
Seventy-eight percent of those with true combat fatigue were returned to duty within
14 days. Only 50 percent of those with pseudocombat fatigue could be returned to duty, and
they had a hi^ readmission rate.
Throughout liie above discussion the basic principles of immediacy, proximity, and
expectancy are discerned. These principles became the cornerstone of community psychiatry
and crisis intervention as military psychiatrists returned from war to civilian life.
Psychiatric Emergencies
True psychiatric emergencies are those that require the extreme of interventions in a
patient's life - providing him with prosthetic controls, either chemical or structural, namely,
hospitalization. This provides Mm controls over his impulses when his are insufficient for his or
others' safety. Hie situations that meet these criteria are those of confusion and impending
suicide or homicide.
Confusion, as an emergency, means that the patient is unable to manage his life. In
treating it, the physician must distinguish between organic and functional etiologies and
treat accordingly. Helpful in this regard is a history from a reliable mformant and the
signs that are characteristic of CNS involvement - disturbance of orientation, memory,
intellect, affect, and judgement, and visual hallucinations. Auditory hallucinations are more
typical of the functional illnesses.
6-26
Psychiatry
The danger of suicide generally presents as ideation, gesture, or attempt. When ideation
presents, estimating the danger of its being translated into acljon is difficult. Determining some
of the following may be helpful:
1. The presence of depression and a hopeless or Weak outlook
2. The loss of friends or relatives, or of self-esteem, or of a body part or function highly
valued by the patient
3. A mode thought out
4. The means acquired
5. A past history of serious suicidal ideation, or of a gesture or an attempt
6. A history of drug abuse (25 percent of suicides are alcoholic)
7. Poor health
8- Th« patient's estimate of risk
9, The physician's empathetic estimate of risk.
Gesiaires are usually associated with personality disorder and manipulation. Attempts are
usually expressions of bona fide depression and serious intent. Treatment depends on correct
dia^osis and a proper response to an estimate of the self-destructive risk.
The risk of homicide may derive either from psychiatric or organic illness and is historically
nearly impossible to predict. If the etiology is functional, the following have been associated
with increased homicidal risk:
1 . Brutal parents, especially the father
2. A borderUne or schizoid patterri of adjustment
3. A seductive mother
4. A triad of cruelty to animals, fire setting, and enuresis
5. A paranoid pattern of adjustment with chronic anger. If the illness is organic, there may
be increased risk where the basic personality pattern has been paranoid.
The Center for the Study of the Prevention of Violence in Los Angeles has uncovered a
rather high percentage of soft neurological signs in studies of violent patients, about 42 percent.
In tfie individual fease, an estimate of the following may be helpful in assessing homicidal
potential:
1. The degree of unreality in the paranoid ideation
2. The adegwgcy of contact with reality in general
3. The intensity of anger
6-27
U.S. Naval Flight Surgeon's Manual
4. Hie history of impulse control
5. The adequacy and stability of relationships
6. Self-esteem
7. The presence of the paranoid defense as a major coping device
8. The patient's estimate of his current control.
Studies suggest that only a very small percentage of those presenting with homicidal risk
ever act on their impulse. Treatment consists of the imposition of chemical and/or physical
controls (in the form of hospitalization) as in suicidal potential, until the danger is over.
There are two other types of emergency with which the Flight Surgeon will surely be
confronted, but they differ in character from those described above. The first is that of the
distraught, and perhaps lonely and dependent, military wife whose husband is at sea or overseas,
possibly in a combat area, and the second is that of the young military wife who has just lost
her husband in an aircraft mishap or in combat.
In the first type, the emergency may either be real or the expression of immaturity and
predominantly intrapsychic factors. If it is real, the social worker may be the proper helping
person. If it is not, the Flight Surgeon psychotherapist may be necessary and perhaps the social
worker as well, if the husband must be returned and/or the children need care or supervision.
For the stress of military separation, prevention, in the form of preparation of the family by the
mUitary member, is by far the best form of treatment. This should include emotional
preparation for his absence and the necessary shift in roles, agreements for communication by
writing or other means, power of attorney for legal problems, and plans for adequate residence,
medical care, financial, and other crises that may arise. Knowledge of the yarioHS helping
agencies and what they can realistically do should help to aUay separation anxiety and forestall
emotional crises.
At some time the Flight Surgeon will surely be called upon to accompany the chaplain and
the comman<fing officer to notify a young wife of the loss of her husband in an aircraft mishap
or in combat. Recalling the stages normal to grief reactions, he will realize that one of the most
unportant elements of treatment is helping the patient and encouraging the relatives to help the
patient to experience, ventilate, and express her feehngs, whatever they may be. Sedation or
tranquilization should therefore be minimal, but the patient needs at least enough sleep to
function. Prescribing Dalmane, 30 mg HS, for several nights may be very helpful in supporting
the patient through the most trying period. It may also be important to have a fiiend or relative
of the patient's choosing stay with her for a day or so, particularly if she would otherwise be
done.
6-28
Psychiatry
The Psychology of Survival
With today's ultramodern communications and locating devices, one is much less likely to
be faced with surviving in a hostile geographic enlirottttlfttit fhall afr: A pimm<3^"m (POWJi;
Soine of the Wpful techniques and^ eoiieepts that hive he6n learned or proven ttom
Vietnam experience are included in this discussion from the point of view of a captured piot.
Family Preparation
A family's ability to face and survive a long period without the head of the family will be
measurably enhanced if they prepare for it ahead of time, before his deployment. In the event
of capture, the prisoner can then be somewhat less worried about how his family is managing.
The military member should prepare his wife and children, within the limits of their emoftbnal
comprehehsidn, for Ifhe sl^ft in responsibilities and roles that his absence will entail. He should
consider granting ]^tj#er' Jst aMtriey aiid pirep^e Ms wife for any legal problems that can be
foreseen. He can provide plans for residence, medical care, financial, and other crises that may
arise hi the event of his captiire and imprisprmient
Shootdown and Culture Shock
For a few pilots shot down in the Vietnam conflict, the abrupt transition from the highly
ordered, time-structured, mechanized world of the cockpit to the anachronistic, agrarian,
illiterate worHd^j^itb^ pgs^ fwas momentarily cHssK^aiBtog, praducing a feeMng^of .unreality.
Th».,:f ^i^ ug^ fiiHS^s^ about laying realistic plans and trying to cope, even though
captured. The best preparation for this stress should be SERE (Survive)., Evasion, Resistance,
anil^jaiije) school. . ,.
Coping in Captivity
There are many things that one can do in captivity t6 eflhanee the abttty'to^SUll^i^e;
theiJpeatest sii^e shock to the P6W iv8S>b*6«M&S'Wd^if torture, and *e unbelievjsble
rapidity with which it could happen. It 8iia|»ly dii^«fit Tiith the POW's image of himself as a
red-blooded, American fighting man. This rent the man from his identification with his ^oup
and produced enormous guilt and depression that could usually only be alleviated by sharing the
experience with a fellow POW. His understandmg and encouragement brought lifep*te#ttttrf
and repaired tlte rift.
Alto^fh the Code of Conduct was a rallying point, it was meant to be applied flexibly, and
it is so stated in the Code. Those who apphed it rigidly because of their early SERE training
were prone to be broken needlessly over information or behavior of minimal value. Unified
6-29
U.S. Naval Flight Surgeon's Manual
resistance was extremely important for morale, and it made each POW much less vulnerable to
the enemy's blandishments and torture. But, the POWs soon learned that it made more sense
mt to resist to the point of confusion or insensibility h^m^, then, one might give tndy
v^uabte informatioR to the Jiapt4»r mth0^t |ealW»gat« It itte better to stop just short of that
point and give some mideading or useleas bit of ilif ormatioii.
In the oriental environment of Vietnam, saving face was an important concept in the
^ve^wd-take with the captor. If the captor was required by his superiors to extract a bit of
inf ormafion or behavior |roni a POW, he had to return with something. It did not mat^' what it
was or, at tim^, even whether it made sense. Knowing this could sometimes saVe a P(0
needless injury. Conversely, if one could figure out how to put the captor in on6*fl debt, the
face-saving concept could again be turned to advantage for the POW, with the captor
overlooking some bit of forbidden behavior or perhaps providmg medical care.
Saving face was also a problem for some of the I*OWs who felt constrained to "go to the
mat" at the slightest provocation from their captor. It often took several beatings for a POW to
realize that this was a foolish and losing game and that pride consisted of mote important
thmgs.
' Torture could be and was appUed again and again over weeks and months. The POWs
learned ronj^y how much they could endure btef<jr» bfeistyinf 5 'tfiat they could recuperate, and,
depending on the gravity of the iMjuiteSinflajted, about how long it would take. 11%-^adually
realized that one could survive even extensive torture, and this in itsdf i waff reassuring. This
realization underscored the importance of keeping fit to improve to the utmost one's
recuperabihty. Three or four hours a day might be devoted to physical fitness exercises of
various sorts. POWs soon appreciated that "healthy bodies meant healthy minds." Food was
equally important in this regard The POWs learned to eat things-lfcat wm mjimally revolting,
though of some nutritional value. It has been shown from earUer wars that we^t loss in
captivity was the only apparently significant variable which could be related to disability which
developed as late as ci^t to ten years after repatriation. . , . 1 / :
Shortly after capture, the POW was tortured to extract short-Uved information. Then, he
was normally isolated, sometimes for months, even year& Tis ai^fl boredom, depression, or a
break with reaUty, the POW had to "keep busy." This could be done either inside or outside
one's head. One had to be involved, to move into some kind of future, even, paradoxically, if it
meant exploring the past. One of the first things a POW did was to go over his entire life,
piecemeal. This might take three to four months; the longer, the better. He would recall events
or people he had not thought of in years. He might, for example, recall everyone in his third
6-30
. Psychiatry
grade class. He reevaluated all the decisions and choices he had made. Sometimes major shifts in
values occurred. It was a private psychoanalysis. This process could be repeated several times
before it burned itsdf otft-iThen, the POW mij^t engage in imaginary activities, such as Iptttoi
an entire housing subdivision or a house or a truck, brick by brick or bolt by bolt OtheJs who
could communifeate' staged lar^ages, history, m phiofidifphy, played chess or worked calculus
problems. Some studied the local insects, playing games or experimenting with them. Depressing
thoughts had to be avoided. As one POW put it, "they could ruin your day."
The need to coiQmUnieate with fellow prisoners was so strongthat oileiWiould risk torture to
do so, and all sorts of measures were devised. A tap code eoidid be seiit.hjs.tapping, sweeping,
spitling^.eOTi^n^'Stc-^^ GarboffliOt the lead from too^
in secret hiding^iplaeeSi, ■ "•
Communication was the cornerstone of another basic necessity for survi'Kal,-^<mtf and.
group identification, with a hierarchy of leadership. As one POW put it, war with the enemy had
not ceased upon ejection from his aieeraft; only the mode aftd the front had changed* A® "'Home
With Honor" was the slogsm for survival, unity and communications were the means by which it
was achieved. If a man was not incorporated quickly into the communications network, he was
fair game for the enemy to divide and conquer. The tactics of the captor were to find weak hnks
among the POWs and then to persuade them to collaborate either by force, leniency, deception,
or blackmail. Leaders especiaUy were their targets, and they sufi^dM©irti;4^fe«f W€fe isdsttedi
for several years to sequester them from their men and subjeeted to frequent and mtense
torture.
In this connection, the prisoners were subjected to incessant propaganda and classes in
Communist ideology. Most authorities reject the term "brain-washing" because it suggests that
by some magical and nefarious means the prisoiie*'^ naWd is;erased dean of f®i»tte*i^rW@toB&
anfl loyalties, and these ^feiupplanted by Coirimunist ideology and attitudds^sp^sed willii^.
and permanentiy. They prefer the tenn "thought reform," which is a lengthy process of
confession and persuasion in a group setting by the behavioral conditioning of reward and
punishment. Successful thought reform, however, requires that the prisoner have been brought
up in an environment where group orientation is a very stiong and potent force for influence.
The methods of the Vietnamese capt0M were regarded ats ^le. if Welti and were
essentially ineffective. A^ ^topaganda that appeared to haye been ibsoKfeed was quickly
repudiated when the pfessure-was removed. The few exceptbns were those POWs who had been
extremely naive, passive, rootless, or isolated in their own countries, with no firm convictions or
loyalties to begin with.'
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U.S. Naval Flight Surgeon's Manual
In other times and places, more forceful and relentless tactics, such as drugs, sensory and
sleep deprivation, torture, and endless interrogation were applied to a few persons with results
that might be termed "brainwashing," but even here there is room for doubt.
This does not mean that one cannot be made to lose one's sensibilities for a time, to become
disoriented, or even subject to halludnatiQnSi but at least one can be reassured that this is not a
permanent state of affairs.
Otganic brain syndromes with hallucinations occurred in the context of physical abuse,
sleep deprivation, or malnutrition, or a combination of all of them. Yet, they remitted, and at
the present time there is no sipi of residua post repatriation, again providing reassurance that
one can survive and even recover from enormous amounts of physical abuse and torture.
Realizing this ahead of time can add to one's survivability by relieving a person of much of the
fear of anticipated permanent disEdjility.
Sexual functions appeared not to be a problem in captivity or after repatriation as some
prisoners feared.
Some POWs worried about dreaming at first, until they discovered that they only dreamed
pleasant escape dreams. These dreams always ended, however, with the necessity for returning
to tto-prison environment. When one prisoner in his dream reftised to go back, he claimed he
never dreamed again in captivity.
There is a suggestion that a certain amount of time, somewhere between six weeks and six
months, was required to adapt to the shock of capture and captivity. The time was necessary for
anxiety and depression to subside to at least tolerable levels so that the individual could begin to
function again, to move ahead in his daily life, and to contemplate a future, however uncertain
and bleak. A few who were repatriated with a shorter period of captivity were still likely to be
quite anxious and to have d^culty deeping^ making decisions, performing complex manual
tasks, and thinking, concentrating, and remembering. This may be an aspect of the initial
depression because the symptoms are similar to those of any typical depression, and the time
required to adapt reflects the time typically required to recover from an untreated depression in
any other setting. Frequently, this period of depressive symptoms was terminated, often rather
abruptly, when the prisoner made a firm decision to survive and be^n to look and plan ahead.
Recovery was especially facilitated by the relief of sharing his initial capture arid torture
experience with a fellow POW.
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Psychiatry
Repatriation
In captivity, time to think, to ponder, 1» delSttfirtte, to make the most iitiittilte,
inconsequential decision, was abundant, ^en r«paftiatioa ibxMf occUEred, the pressure of
events and people and, by contrast, the frequent demand for rapid, important decisions and for
equally rapid role reintegration resulted in reentry or reverse culture shock, nearly as devastating
for a few as the initial one. This might last from as little as a month to as long as a year. It was
variously reflected in persistent anxiety, insomnia, indecision, depression, difficulty driving, and
for a few, excessive drinking. But in most cases, marital d^ctird was the commonest expression.
This discord was often intensified by unconscious hostility on the pjart of the wi^ over having
been abandoned (during captivity) and was compounded by her realistic anger if the repatriated
prisoner of war (RPW) seemed thoughtlessly to allow his time to be monopolized by
well-meaning relatives, friends, and well-wishers, numerous banquets, public appearances, and
requests for speeches to which he felt obligated to respond. Regardless, the great majority of the
RPW's negotiated repatriation successfully.
Conclusion
Personality and temperament are undoubtedly hupOiSant varfabte not didy iii coping with
torture, but also in unwittin^y inviting it. The Center for Prisoner of War Studies is exploring
these variables and their relation to resistance postures. Does the hysteric unconsciously invite
torture by "going to the mat" at every provocation no matter how slight; does the passive or
schizoid person escape attention; is the compulsive person more apt to capitulate and cooperate
or, through rigidity, to bring excessive torture upon hiotnaelf? How does the intensely sen^tive
person fare or the calm, tough-minded individual wifih a Ji^ thijeshoid for anxiety and pain?
In retrospect, it would appear that survivability from shootdown to repatriation ultimately
depends upon and requires recovery of self-esteem through reintegration with the group - the
POW group in captivity and the miUtary, the family, and society-at-large upon repatriation, to
the degree that there is faUure in this, there will be symptoms and signs - psychopathology.
References
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1946.
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Ban, T.A. Alcoholism and Bcldzophrenia, AteohoiMfw, 1977, J , 113-117.
Banduia, A., Grusec, J.E., & MeiJove, F.L Observational learning as a function of syniboBzation and incentive
set. Child Development, 1966, 37, 499-506.
6-33
U.S. Naval Flight Surgeon's Manual
Ban4ara, A., Ross, D., & Ross, S.A. Transmission of aggression through imitation of aggressive models, iournai
iif Abnormal and Social Psychology, 1961, 63, 573-582.
Bandura, A., & Walters, R, Social learning and personality developrmnt. New York: Holt, 1963.
Benzodiazepines. American Journal of Psychiatry , 1977, 134, 652-672.
Chapel, J. Emergency room treatment of the drug-abusing patient. American Journal of Psychiatry , 1973 130
2S7-2S9. J .7 j> , ,
Department of the Navy, Bureau of Medicine and Surgery. Dffiposition of rehabilitated alcoholic aircrew
personnel and air controllers (BUMEDINST 5300.4A). 19 April 1977.
Dewaid, P.A. Psychotherapy. New York: Basic Books, 1971.
Greenblatt, D.J., & Shader, R.I. Drug abuse and the emergency room physician. American Journal of
Psychiatry, 1974,, 131, 559-56K
Holinger, P.C., & Klawans, H.L. Reversal of tricychc-overdosage-induced central anticholinei^c syndrome by
physostigmine. American Journal of Psychiatry , 1976, 133, 1018-1023.
Holloway, W. Seminar on script analysis in transactidnal analysis. American Psychiatric Association Annual
Meeting, 1977.
Kelly, G. The psychology of personal constructs (Vol. 1). New York: W.W. Norton, 1955.
Langs, R.J. The technique of psychoanalytic psychothempy (Vol. T). New York: Aronson, 1973.
Lazarus, A. Behavior therapy and beyond. fiem York: McGraw-Hill, 1971.
Lazarus, A. Multimodal behavioi therapy: treating the "basic id." Journal of Nervous and Menttd Disease,
1973,196,404411.
Munoz, R,A. Treatment of teicyclic intoxicatiou^jlmcrican Journal of Psychiatry , 1976, 1 33, 1085-1087.
Reinhardt, R.F. Fear of flying, ftresentation at the Annual Meeting of the American Psychiatric Association,
May 1965. d . ,
Reinhardt, R.F, The outstanding jet pilot. American Journal of Psychiatry, 1970, 127, 732-735.
Sadock, V. Marital therapy. In B. Sadock, H. Kaplan, & A. Freedman (Eds.), The sexual experience. Baltimore:
The WilKams and WiUdns Co., 1976.
Small, L, The briefer psychotherapies. New York: Bmnner-Mazel, 1971.
Strange, R.E., & Arthur, R.J. Hospitd ship psychiatry in a war zone. American Journal of Psvchiatrv. 1967
i24, 281-286.
Thomas, A., & Chess, S. Temperament and development. New York: Brunner-Mazel, 1977.
U.S. Naval Flight Surgeon's Manual. Prepared by BioTechnology, Inc., under Contract Nonr46l3(00). Chief of
Naval Operations and Bureau of Medicine and Surgery. Washuigton, D.C., 1968.
Wachtel. P.L. Psychoanalysis and behavior therapy: toward an integration. New York: Basic Books, 1976.
Wolpe, J,, & Lazarus, A. Behavior therapy techniques. New York: Pergamon Press, 1966.
Zetzel. E.R. Current concepts of transference. /nternationaZ/oitrnd of Psycho-analysis , 1956, 37, 369-376.
Bibliography
Appleton, W.S. Third psychoactive drug usage guide. Diseases of the Nervous System, 1976, 39-51.
Chessick, R.D. How psychotherapy heals: the process of intensive psychotherapy. New York: Aronson, 1969
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Psychiatry
Dahlstrom, W.G., & Welsh, G.S. An MMPI handbook: A guide to use in ctinical practice and research.'
MiimeapoliB: University of Minnesota Press, I960.
DaMstrom, W.G., Welsh, G.S., & Dahlstrom, L.E. An MMPI handbook. Volume 1: Clinical interpretaHon.
Minneapolis: University of Minnesota Press, 1972.
Freedman, A.M, & Kaplan, H.I. Comprehemioe texthmk of psychiatry. Baltimore: The WiUiwns &
Willdm Go., 1975.
Greenson, R.R. The technique and practice of p^choamdym (Vol I). New York: International Universities
Press, Inc., 1967.
James, M., & Jongeward, D. Born to viin: ttmstastioml analysis with gestalt experiments. Reading, Mass:
Adason-Wedey, 1971.
Kaplan, H.S. fke new sex therapy. New York: Quadrangle, 1974.
KeSiberg, O.F. Object relations theory and clinical psychoanalysis. New York: Aronson, 1976.
Kolb, L.G. Modern clinical psychiatry. Philadelphia: W.B. Saunders Co., 1973.
Langer, J. Theories of development. New York: Holt, Rinehart, & Winston, 1969.
Langs, RJ. The bipersonal field. New York: Aronson, 1976.
Langs, R.J. The technique of psychoanalytic psychotherapy (Vol. II). New Yo*: Afonson, 1974.
MacKinnon, R.A., & Michels, R. The psychiatrk interview mcKitfcoIj>melice. Phaad%h»: W;B. Saunders Co.,
1971.
Mann, J. Time-Umited psychotherapy. Cambridge, Mass.: Harvard University Press, 1973.
Mullin, C.S, Combat psychiatry in the field. U.S. Navy Medical Newsletter, 1964, 44, 3-10.
Nemiah, J. The foundations of psychopathology . New York: Aronson, 1973.
Pincus, J.H,, & Tucker, G.J. Behavioral neurology. New York: Oxford University Press, 1974.
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U.S. Naval Fli^t Surgeon's Manual
APPENDIX 6-A
OUTLINE FOR PSYCHIATRIC REPORTS
The outline for consultations and reports should correspond to the traditional medical
format:
1. Identifying information and symptoms/signs (CC)
2. Patient profile according to the PROMIS system
3. Context — event or situation precipitating the symptoms/signs (PI)
4. Background history ~ the personality (pjjj
5. Mental status examination and psychometiics (PE)
6. Summary statement correlating 1, 2, and 3 (Dx)
7. Diagnosis and complementary statements
8. Recommendations; therapy plan. ^^^x)
F6r brevity's sake, certain phrases and items of information should be constant. They
appear in italics.
Paragraph 1. This year old (mtntal status), (rank/mte), USN(R), with about
years of continuous active (broken) service, was referred for psychiatric evaluation on
(activity) . with the diagnosis
because of (symptoms /signs) . Much of this
information may and should be in the upper half, or referral portion, of tiie SF 513 written by
the referring physician and need not be dupbcated.
Paragraph 2. The Patient Profile. This is an outiine of the patient's everyday world and tiie
routine responsibiUties and burdens he bears which may affect his responses to the
"precipitating stress" and to treatment plans.
Paragraph 3. Portray the context precipitating the above symptoms/signs. In otiier words,
develop what has been going on in the patient's life that has given rise to the symptoms or signs
of the present iflness, how and why it led to referral, and the patient's goals with regard to tiiis
interview. The context will often reflect the fact that tiie patient is being confronted by the
challenge of a major niUestone or state in his psychosexual/psychosocial development. If
disciplinary action is at issue, develop detaUs reflecting competency. Contrast illness witii assets
in present functioning.
6-36
Psychiatry
Paragraph 4. A review of his background, as elicited from the patient (and whiaievdf other
reliable sources), turn considered (how) reliable and revealed a - * t-i:- pattBtn
of adjustment. A single Sentence introductory stateBi^ji|t oi Ij^e patient's predpminant defensive
character trait{s) or behavior pattern(s) will be helpful to the reader. Choose wording here that
will relate and point to the final diagnosis, e.g., "passive - aggressive pattern of adjustment."
The purpose of this paragraph is to dehneate the genesis of a core conflict, the history of
re-enactments of it, and the pattern of the patient's defensive behavior erected against it up to
present illness or present peraonaKty conWlc't^'tK^k'wl^ai£^e & personality pattenivand by
inference the later intended diagnosis, stand out in bold relief. It may also be appropriate to
note the patient's sucoesses in negotiating the various stages of development and fiftrresponding
assets pointing to a relatively normal personality pattern.
Be sure to editorialize, not just repoiit; preface or follow, where possible, the description of
the patient's behavior with a psyehodynantic interpretation. Trace psychosexual/psychosocial
development and deviations or arrests. Search for prior examples of the patient's characteristic
mode of reacting, or perhaps their absence, simply because he narrowed his life relationships or
fortuitously was never stressed in his particular areas of weakness or conflict. Also clarify, by
inference only, the EPTE status of his iilness in this paragraph. The following items need«,t® be
included only insofar as they contribute to highlighting the pattern and to m undei^tandljttg <jf
the expression of it: ' '
1. Socio-economic setting of birth, early life, and school years
2. Family constellation and relationships
a. parental (occupations)
b. siblings
c. parental surrogates
3. Early childhood
a. memories - emotional atmosphere, proscriptions, prescriptions
b. early neurotic determinants . t. , • '
4. School adjustment
a. superior
b. peers
c. academic, athletic, leadership, extfacuimtlalar
d. discipHiiary
5. Work adjustment
a. how many jobs
b. attitude
c. why left
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U.S. Naval Flight Surgeon's Manual
•6. Military adjustment
a. motivsatioii for entry at particular point in patient's life
b. relatidns with superiors, peers, subordinates
c. servi©^ jacket information
1) Wtt ■
2) quarterly marks
3) letters of commendation or reprimand
4) disciplinary actions
7. Social adjustment
a. interpersonal relations
b. free time activities - recreation, hobbies, interests
c. civil disciplinary action
8. Religion - its effect, any changes
9. Sexual - Marital (there is almost always a disturbance here.)
10. Health - emotional components of organic disorders
11. Dreams and recurring dream themes
12. Future plans and aspirations and appropriateness.
Paragmph 5. On mental status Bxamination, (s)he. . . Give briefly the following pertinent
elements:
1. General appearance
2. Psychological functioning
a. openness - defensiveness (where is the patient open and free in his worid, with self
others, things, the examiner, his God, and where is he in conflict and defended and
unfree?)
1) ego strengths - freedom, openness, and authenticity
2) ego defenses - constriction, immaturity, and inauthenticity
a) mechanisms of defense
b) immature personality patterns
c) abuse of drugs
d) neurotic symptoms
e) psychotic symptoms
b. affect
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Psychiatry
relationships - the patient's involvement with or attitude toward his world - self
(self-image or esteem), others, and things (object telntions). Where aitd 'VSfith whom
he is relatively open, free, and authentic, and where and with whom he is unfree and
anxious, in conflict or alienated. His motivations, attractions, inhibitions, con-
strictions, fixations, regressions, and manipulations and his ideals, values, and
prohibitions should be discussed. Is he moving ahead normally into his future; is he
caught in his past (depressed); is he more absorbed in the world «rf things than
people (schizoid); is he totally detached from his world (psychotic); is he still
entangled in oedipal conflicts and avoiding heterosexual relationships, or, with
unresolved dependent ties to his nuclear family, is he avoiding success, in-
dependence , and heterosexual intimacy, etc.?
Organic brain functioning
a. motor behavior
b. sensorium
1) level of consciousness
2) attention
a) jepiMpiftK^on > .|.,,.
4) oiiw^atiajti - time, place, person, context
5) memory - fund of general information, vocabulary
a) immediate recall
b) recent
c) aremote
c. perception
1) illusions -,.
2) hallucinations • . ^
3) other alterations
d. speech ' ' '
1) quality, rate, flow
2) persifglitaons
'5t)*'a{^i^ai^ydi*afjhMiias ' •. • : • • ' ' ,
e. synthetic functions
1) imagination - ability to fantasize
2) abstractive abiUty - simUarities, differences; proverbs - concrete, abstract,
1 autistic, bizarre, irrdewint
3) G6mpf€hensi0ft
4) reasoning
5) calculations
f. IQ estimate
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U.S. Naval Flight Surgeon's Manual
4. Judgment
6. Pbtetitial for therapeutic alliance.
Rather than dutifully listing the many elements of an exhaustive mental status examination,
strive to organize and emphasize those observations in the here-and-now of the mental status
^^dihmation that reflect (1) the patient's presenting iUness, defensive behavior, or problem and
(5) his basic personality (relatively enduring beKavior patterns and defenses and psychosexual,
psychosocial development level).
Psychological tests revealed (or suggested)
Paragraph 6. Summary statements. Here it is desirable to have a dynamic formulation tying
symptoms/signs to contex;t to personality.
Paragraph 7. Diagnosis. If appropriate, this should include the complementary statements
of code number, degree, acute/intermittent/chronic manifestations (refer to American
Psychiatric Association, Diagnostic and Statistical Manual 11) stress, predisposition, impairment
for military service, and, if disciplinary action is pending, a competency statement.
The current form of the competency statement is as foUows: "It is the opinion of this
examiner that, at the time of the alleged offense, the accused was so fa* feee from mental
defect, disease, or derangement as to be able concerning the particular acts charged to
distinguish right from wrong; and, at the time of the alleged offense, was so far free from mental
defect, disease or derangement as to be able concerning the particular acts charged to adhere to
the right; and does possess sufficient mental capacity to understand the nature of the
proceedings against him and inteUigently to conduct or cooperate in his defense. Further, it is
the opinion of this examiner that disciplinary action in the form of confinement is (not) likely
to have a deleterious effect on his (her) health, and disciplinary action probably would (not) be
corrective and (nor) lead to a better service adjustment" {Manual of the Medical Department,
Chapter 18-12, (1), (a)).
Paragraph 8. Therapeutic plan. If appropriate, recommendations for administrative disposi-
tion in accordance with current BuMed and BuPers, or Commandant, Marine Corps, directives
should be included.
640
Psychiatry
Brevity and clarity are of the utmost importance. General statements mmt be supported by
one or more facts. It is not that brief write-ups are sought per se, rather, an overiy lengtiby tome
strongly su^ests that the author lacks a clear and shsflfp understmiding of Ms patient and his
problems in living, and that he has thrown everything into the pot in the sometimes vain hope
that he has included the morsel of meat. The goal throughout should be to highlight those
aspects of the patient's Ufe that are sets or points in the pattern of malfunctioning or
maladaptation that the author is attempting to lay before the reader. A terse exposition of a
patient's proKleinS in Uving, however, will probably red(jiind more to the author's and his
patient's benefit than to anyone else's up the administrative ehain of typing and review.
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U.S. Naval Fli^t Surgeon's Manual
APPENDIX 6-B
PSYCHOLOGICAL TESTING
Minnesota Multi-Phasic Inventory <MMPI)
Of the several psychological tests us^ in Navy psychiatry, the MMPI is probably the most
popular. Its popularity is in part a function of its ease of administration, scoring, and the
amount of data it provides. However, the MMPI, hke all other psychological tests, is an
imperfect measuring instrument and should be used with caution. A diagnosis cannot be made
on the basis of the results of an MMPI score on any one scale or even the entire profile; other
factors, such as background history, mental status, reason for referral, the general context of the
testing situation, must be taken into account.
At the NAMI Psychiatry Chnic, a short form of the MMPI (408 items of the standard
550-item test) is administered routinely to new patients. It is scored and given to the doctor
along with the patient's Psychiatric Interview Questionnaire and, as appropriate, the patient's
service record, health record, and flight record. The MMPI is interpreted in the context of these
other data, including the psychiatric interview. The information provided by the MMPI should
alert the physician to hypotheses about the patient which might be otherwise overlooked in the
interview, rather than to bias his impressions.
The MMPI is scored separately for males and females because the normative data are
different. Scores are T-scores, i.e., the mean is 50 and the standard deviation is 10; thus, a score
of 50 is average while scores of 60 and 40 are one standard deviation above and below the mean,
respectively. As a general rule, scores two standard deviations above or below the mean
(70 and 30) are considered significantly high or low enough to be interpreted; those scores in
between are not interpreted alone but in relation to the other scales above 70 and below 30.
There are four validity scales and ten clmical scales in the hasic MMPI personality profile. In
addition, there are a number of experimental scales and new scales which are reported in the
literature from time to time. These will not be considered here. Figures 6-A, 6-B, and 6-C
present the expected profiles for scores in the direction of a majority of normals (Figure 6-A),
opposite to the majority of normals (Figure 6-B), and m a random response (Figure 6-C).
Validity Scales
"Cannot Say"(?) Scale. These are test items that the patient has left blank. As a rule, 30 or
more blanks invaUdatC the test. It is often useful to note the blank items and ask the patient
why he left them blank. It is also helpful to notice if there is a pattern to the omissions
e.g., religious, sexual, etc.
6-42
Psychiatry
90 ■
70 •
Figure 6-A. Expected personality profiles when each item is answered
in the direction of the majority of normals.
"Lie" (Lj Scale. This scale measures conscious, though quite naive, deceplion when the
patient answers too many, seven or more, of the 15 items in the "Ue" direction. A high score
shows a tendency to put oneself in a favorable U^t; therefore, presumably, such a tendency
would ateo operate in answering the items on the other scales. High scores on the L scale
identify people characterized as naive, rigid, and lacking insight.
F Scale. The items in this scale express a broad spectrum of maladjustment, reflecting
apathy, peculiar thoughts and ideas, and denial of close social relationships. The F scale
correlates positively with degree of pathology (Figures 6-A and 6-B) and severity of stress, but
high scores also suggest faking (trying to look bad or a "cry for help"), random response to the
test in a deliberate lack of cooperation (Figure 6-C), scoring errors, or an inability to read or
understand the test items.
/
/
6-43
U.S. Naval Fli^t Surgeon's Manual
' t I — I t — t ■ ■
1 2 34567 890
L F K Hs D Hy Pd Mf Pa Pt Sc Ma Si
Figure 6-B. Expected personality profiles when each item ie answered
in the direction opposite to that of the majority of normals.
"Correction" (K) Scale, Responses to K items show a tendency to deny personal and
interpersonal problems; therefore, a high K-score is associated ' with lower clinical profiles
reflecting this denial and defensiveness. To correct for this tendency, points (proportional to the
K-score) are added to certain scales which have been found to be particularly easy to fake.
Moderately high (55 to 65) scores are correlated with high self-esteem, intelligence, socio-
economic status, and educational achievement, wMle low scores (below 40) suggest poor
self-concept, anxiety, and over-inhibition. Thus, in aviators it is common (and desirable) to see a
K-score around 60. Above 75, defensiveness is maladaptive.
Qinical Scales
Scde I: Hypochondriasis (Hs). Contained in this scale are obvious physical-complaint items
which reflect preoccupation with bodily health not restricted to any particular part of the body.
644
Psjrcfaiatry
These igeftaplailfttl- may or may not be organically based, but if so, the scale score is
arduttd 55 to 65, usually with an elevated scale 2. If scale 1 is the highest peak on tlic jirofile,
organically based complaints are unhkely, and the patients are described as self-centered and
demanding.
L F K
Figure 6-C. Expected peffiobality profQes from a raitdom teepolise to items.
Scflfe 2: Depression (D). This scale is one of the least stable of the MMPI, being sensitive to
transient emotiond slates, md tefl^cts low fliotale, feelings of hopelessness, physical
malfunctioning, raoodin^s. In and of iteelf, an elevated scale 2 does not predict suicide, but
if scales 4, 7, or 8 afre also elevated, tjlen the potential increases.
Scale 3: Hysteria (Hy). Two contradictory types of items are contained in this scale which
are found in people described as "hysteric," physical complaints and social well-being. The
somatic items from this scale and scale I are correlated but are at the same time different in
6-45
U.S. Naval Flight Sutgeon^ Manual
their emotional tone. It is rather flat, "la belle indifference," in many hysterics. High scores on
this scale suggest naivete, immaturity, egocentricity, and a tendency to develo^p conver^on
symptoms when under stress.
Scale 4: Psychopathic Deviate (Pd), This sqale was developed to measure a predisposition to
impulsivity, low frustration tolerance, social maladjustment, and other sociopathic traits. It is
common to see this scale a high-point among adolescents, reflecting age -appropriate conflict. In
otherwise normal people, an elevated scale 4 can reflect adventurousness, sociability, indi-
vidualism, and assertiveness.
Scale 5: Masculinity - Femininity (Mf). Both masculine and feminine interest patterns are
reflected in this scale. For either sex, high scores simply indicate an interest pattern in the
direction of the opposfte sex and, in themselves, are not sufficient eviteilde of homosexuaUty,
latent or otherwise. Males whose scores fflfe elevated are seeniis sensitive, imt^atiye, and having
a wide range of cultural interests. There is a positive correlation between level of education and
intelligence and a high score on the Mf scale. Females whose scores are elevated are seen as
aggressive and competitive.
t ■
Scale 6: Paranoia (Pa). The clinical picture of a "paranoid" person — hypersensitivity,
suspiciousness, rigidity, delusions of persecution and grandeur — is contained in this scale which,
in general, taps the dynamics of the defense mechanism of projection. Very high scores may
su^st a ffisabling level of psychopathology.
Scale 7: Psychasthenia (Pt). Anxiety is the primary characteristic measured by this scale.
Insecurity, feelings of guUt, low self-confidence and self-esteem, and obsessive-compulsive traits
are also present in those who have hi^ scores on scale 7.
Scale 8: Schizophrenia (Sc). Even with a score above 70, a diagnosis of schizophrenia
cannot be made on the basis of this scale alone. This is true of all MMPI clinical scales and is
repeated here for emphasis. High scorers usually feel socially and emotionally alienated, are
withdrawn, and have an active fantasy life.
Scde 9: Hypomania (Ma). Scale 9 items reflect aspects of an elevated mood, such as
expansiveness, excitement, distractability, and restlessness. Among a normal population, scale 9
devation su^ests sociable, forward, impulsive, adventurQUS people^ With increasing elevation,
the probability of maladaptive hyperactivity and agitation al»^ increases.
Scale 0: Social Intmversb^n (SI), This scale straightforwardly measures social introver-
sion/exl^oyer^on. People scoring low on SGal<@ 0 we extroverted, self-confident, and comfortable
in social situations. High scorers are wofrisome, insecure, inhUiitecl, and kck poise in social
gatherings. ■
6-46
Psychiatry
Profile Interpretation
Because inavitiual scales are rarely elevat«d alone, certain combinations of scale elev^tiQWS
(profiles) will be described. . .
1-3 Profile. Scales 1 and 3 are elevated while 2 is down (figure 6-D). This profile, the
"contersion V," is common for people who convert pSfcWogical stress into physical
syraptomology. This sometimes involves an organ system, the dysfunction of which will remove
the patient from the stress-producing situation, for example, sudden loss of hearing or visual
acuity (without physical causes) to the extent that it grounds a pUot.
647
U.S. Naval Fliglit Surgeon'? Manaal
4-9 Profile. Sociopatbic personality traits and acting-out are su^ested by this profile
ire6-E). These people have difficulty in conforming to social convention, especially
military regulations, and are constantly in trouble. A 4 - 9 profile with elevations on 6 and 8
helps to identify the explosive personality.
Figure 6-E. 4 — 9 profile, sociopathic traits.
6-48
Psyehiatiy
2-9 Profile. This profile is uncommon but when present can suj^st organic brain
dysfunction which, of course, should be further investigated (Figure 6-F).
90
£ 70
5
50
30
L
2
A
1
Hs
2
D
3
Hy
4
Pd
5
Mf
6
Pa
7
Pt
8
Sc
9
Ma
0
Si
Figure 6-F. 2—9 proftte, possible organic brain dysfimction.
6-49
U.S. Nwal Flight Surgeon V Manual
1 S B^flle. IRMs profile suggests a psychotic process, especially if scale 8 is higher
than scale 7 (Figure 6-G).
1
Hs
2 3 4 5 6 7 ! 8 9 0
D Hy Pd Mf Pa Pt f ' Sc Ma Si
Figure 6-G. 1 —6—8 profile, possible psychotic process.' ■
6-50
Psychiatry
} — 2 — 3 Profile. This is called the "neurotic triad" and is usually accompanied by an
elevation on scale 7 (Figure 6-H). Some type of neurosis is probable. If scale 4 is also high
(above 70), alcoholism should be suspected.
90
o 70
1-
o
50
30
1234567890
L F K Hs D Hv Pd Mf Pa Pt Sc Ma Si
Figure 6-H. 1—2—3 profile, "neurotic triad.
6-51
O '
}
7
o
c
CHAPTER 7
NEUROLOGY
Introduction
Syncope
Headache
Head Trauma
Vertigo ; ^ ■^■■\
Meningitis ' .
Bibliography ' •
Introduction
Neurologic contpkiiits mce encountered frequently in any i^»tiee el M«digbjii When
problems such p h^eadache, syncope, seizures, vertigo, and head trauma are included, perhaps
20 percent or more of all physician visits are accounted for. The majority of neurologic
diagnoses can be made on the basis of a thorough history and examination without recourse to
sophisticated and expendve laboratory studies.
In this chapter some of the more common neurologic problems likely to be encountered by
a Flight Surgeon are reviewed with emphasis on the characteristic, and often diagnostic,
presenting histories. Hopefully, this will aid the Flight Surgeon in arriving at a reasonable
diagnosis prior to additional consultation and result in a rational and clearly-defined disposition
of aviators. The appropriate diagnostic workups are briefly summarized. However, long-term
management of these problems is only briefly discussed, since it is not really pertinent to this
manual. Further details can be reviewed in the references provided, as well as in most major
textbooks of medicine.
Seizures
Seizures are perhaps the most difamatic neurologic problem likely to be encountered in the
aviation community. Since single seizures and epilepsy are not generally reportable medical
problems, accurate demographic figures are not available. From sources such as the population
of military recruits, estimates place the incidence of epilepsy at approximately 1 per 200 in a
population of young men. In the United States today, there Sti befifeveaHai Si #6at tBitt^
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U.S; Navql flight Surgeon's Manual
persons with epilepsy, or about 1 per 100 in the general population. It should be remembered
that these figures refer to epilepsy and do not include single seizures or transient comphcations
of diseases affecting the central nervous system (CNS).
De&iitipm
A mmae h a paroxysittid uncpntrolled 0scha»ge of CNS gray matter causing clinical signs
and symptoms that interfere with normal function. Physicians most often thuik of a seizure
m a grand mal or major motor fit with, unconsciousness and tonic clonic movements. The
manifestations of epil^sy, however, include a far >dder spectmm, with or without ^gnificant
motor signs, such as brief absence attacks and behavioral or autonomic phenomena. An
epileptic prodrome refers to the mood or behavior that often precedes a seizure by several
hours or days. The aura is the first part of the seizure and often is the last consciously
recalled experience of the patient. It is important because its clinical pattern depends on
cerebral anatomy and physiology, and it thus helps to localize in the brain the point of
origin of flie seizure. The ictus refers to the seizure itself . The postictal period is that time
immediately following the seizure that is characterized by behavioral changes such as
di##'i^iiaitl eetnfbsionv seii^pi|i!poseful ictimty or abfii»t<iQiil me^r iffi&VM@M. S^M(^nf 'te£&cB
Ho recurrent seizures and is sylfciiiy^ffious with mMUte disorder dr convulsive disorder. A single
seizure or a seizure clearly due to a transient process which has secondarily affected the CNS
should never be labelled as epilepsy.
Classification
The most useful working classification is based on clinical findings as given below:
Grand Mal — Generalized convulsions
Petit Mal — Brief absences
Focal Cerebral — Motor
Sensory
Psychomotor
Akinetic or Myoclonic — "Drop" or "jerk" spells.
For the purposes of this discussion, akinetic seizures which develop between the ages of
2 and 7 years will not be considered further. Similarly, the discussion will not include petit mal
epilepsy which begins in childhood between the ages of 4 and 12 and usually disappears by the
ag^ ,9f 20 years. Absence attacks occurring in adults are far more likely to be focal cerebral
tprtype*
n
Neurology
Grand mal seizures arise deep within the brain, and their cause is often metaboKc or
unknown. Focal seizures arise tr^m a specific cerebral region and are often caused by a scar,
tumor, or malformation.
Etiologies
Seizures, being a symptom of CNS dysfunction, may haveflm*a6rklsei(USMfcB«ft4^t^
ai tdtsxi^Qri'H&^ht in young iii2ull6.'Btitepsy occurs as a sequ^ iifithin tWo y^^ilii'abi^if'l^
percent of the patieht^ Wh severe, closed head injuries. The incidence rises to 30 to 50 percent
with open head injuries that penetrate skull and dura. Seizures are most likely to occur within
the first year of injury, and over 90 percent of the risk is over by the end of 18 months.
••i • - ■ .'■■•!».•....
Tumors are another seizure cause to he considered in adwlts, Whett 0&tttW^^ tftir
age 20, the patient has about a ten pwcent chance of having a brain tumor. This increases to
about a 15 percent chattce at age SO, including primary and metastatic tumorfe^'Tlte^fi^fe of
seizure is important, since the risk of tumor is 35 percent in adults with focal seizures.
Arteriosclerotic vascular disease becomes the most common cause of seizures after age 50.
In younger patients, collagen itSsdtUiF diseases and A-V ttidfortoatioas may (Sus©; !fi©ijBWi:es.
Infections of the CH#-fd|ty*"ateo ipwoduee seizures or may be responsible fot dantage to l^e brain
resultiif Ife'tetaie'B^fiii^fed. • ' "i; • • ■ ; i.
Grand mal seizures may occur in association with chronic intoxication with alcohol or
barbiturates, almost always during withdrawal or reduction in dosage. Usually, patients
experience one or more seizures or shqart burali of two to ffiii «6kw«S ovei! a perie^-ef i^veral
houM* S to 48 hours «fter cessation of drinking. Of course,, lite ifeizures of any epileptie h^tIp
W®^setted'&f an -M^iIhg iOT w«b^ o* drifiking. ia ijapo^tent ^sfcinction to be made is that
aIcohol-preei|ritat<Sd-»pflep«y lefaites toitieanvtteiht therapy, whereas withdrawal seizures do
not. ' !
Further discusrion of etiologies of seizures may be found in any major* textbook of
medicine.
IHagnosis
The hfetory ofctMned from both the patient and any observers is ^e^^iig^e most important
factor in estabUshing the diagnosis and often in determining the cause of seizures. No effort
should be spared in obtaining all details available. From the patient, questions should be asked
regarding possible provocative causes ('e.g., lack of sleep, missed meals, extreme fatigue, menses,
alcohol, drugs), and aura, ictal experience, and postictal effects. Information ^ouldbe obtained
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U.S. Naval Flight Silicon 's Manual
'from any observers regarding the first sigrt^ noted, tli^ exact patttaA of the attack, (Juration of
"the seizure, and any aftereffects. The patient's pa'^t history, including history of febrile
convulsions in infancy, head Irauma. and prior illnesses should be irnestigated. The family
history should be reviewed for history of epilepsy or other neurologic disorders.
• InitiaJ workup should also include a coajpletje general and neuf ©logic physical examination.
Routine laboratory data should be obtained, including a complete blood count, urinalysis,
fasting and 2-hour postprandial blood sugars, calcium, phosphorous, blood urea nitrogen,
electrolvtes, and blood ethanol levels, if indicated. Chest and skull X-rays are indicated as well
as an EKG. Further workup, including lumbar puncture, EEG, radioisotope brain scan or
computerized tomographic scan, and other contrast studies will generally require transfer to a
major medical facility.
Treatment, and Pisposition of Aviators
Following initial workup, any aviator in whom a seizure is documented or suspected should
be referred for thorough evaluation to a medical facility having the necessary personnel and
laboratory capabiUties. Pending completion of such workup the aviator should be grounded.
Generally , if a diagnosis of epilepsy is established, this will preclude iurtb*?'. a#tiTe duty and will
result in a medical dischOTge following a Physical Evaluation Board. Occasionally, if patient
is approaching 20 years of service and his seizures are adequately controlled by medication, he
may be retained on permanent limited duty provided he can be utiliz(?d in that capacity. In this
situation, the duty limitations preclude control of aircraft or government motor vehicles.
A mow complicated problem is that of the single seizure for which no etiology can be
deti^ttrined. Such cases should be referred to the Special Board of Flight Sm^ons (SBFS) for
evaluation of flight status, after the aviators have been returned to an otherwise fuU duty status
by a medical board. In cases where no clear-cut etiologv or transient precipitating factor is
apparent, aviators are usually considered not physically qualified (NPQ) for further duty
involving control of aircraft. Exceptions may rarely be made in dtuations involving multipiloted
aircraft or naval fli^t officers.
Syncope
Syncope or fainting consists of generalized fiiuscte weakness with an inability to stand
upright and' an impsBrmeht of Conscidusfie^. It liMiQiy rdsiilts ftibift a actfldeii impdirtnent of
brain metabolism most often due to a hyp'oteWve reduction of blood flOw. In contrast to
seizures, syncopal attacks almost always occur in the upright (sitting or standing) position.
There are usually presyncopal symptoms of faintness or giddiness, sweating, epigastric distress,
7-4
Neurology
blurring or dimming of vision, warm face, etc. Often the patient, i^ noted iS.Jte palft-flW
ashen-gray prior to the syncopal attack. The deliberate onset and warning symptoms generaUy
allow the patient to He down and avoid the faint. The usual syncopal attack lasts only a few
seconds with consciousness returning rapidly after the patient falls to the ground. Once
horizontal, gravity no longer hindeig blood flow to tbe brain and symptoms improve rapidly. A
faint is igemi ally not followed by drowsinesa or headache (except, of course, that du@4£^lo@aI
trauma) nor by any period of coi^EufflOn or disorientation as seen poslietaBy. Although
infrequent, a few clonic jerks of the extremities may occur in the course of a syncopal attack,
usually about 10 to 15 seconds after falling to the ground. Clonic jerks are more common if
cerebral ischemia is prolonged by inability of the patient to achieve the horizontal position. This
may occur in aviators strapped into their seats or persons standing in a-lacg© f crowed* If jllie
patient remains in an uprf^t position, fainting may be fatal.
Causes of Syncope
As stated above, most syncope results from a transient impairment of blood flow to the
brain. Cardiac output is reduced, either due to defective venous return to the heart (vasovagal
syncope, postural hypotension, tussive syncope, micturition syncope), mechanical obstruction
of cjaj^ac output (aortic stenosis), or cardiac arrhythmias (Stofces-Adams atti^e^j, eirtopjc
tachycardias). Other causes such as hyperventilation and hypoglycemia may cause faintness, bwt
only rarely cause actual syncope. .
Vasovagal syncope (psychogenic faint, vasodepressor syncope, common faint) is the most
common type and is usually seen in young people, particularly females. It seldom begins after
age 35. Usually, vasovagal syncope occurs at times of physical or emotional stress for which no
pKyaiesd' Kesponge is possible. This type of syncope tends to be recurrent. The tendency to faint
is jnca*as©d if the person is fatigued, hungry, sick, in pain, or in conditions favoring
vasodilation, such as a warm room. Prevention of predisposing conditions and the iaborti^tn of
attacks by assuming a head-down position are the major methods of treatment.
Postural hypotension leads to syncopal attacks indistinguishable from the above, exmpt tii>at
the effect of posture is the cardinal feature. The faint occurs upon arising from a reeumbent
position or following prolonged standing. It is seen most often following a hot bath, after
physical deconditioning such as prolonged bedrest, in persons with varicose veins, in diabetics
with neuropathy, and in persons on certain antihypertensive and other medication,
T^ssdve syncope is a rare form of syncope accompanying a paroxysmal eou^ng i^ell wMch
raises intrathoracic pressure and causes decreased venous refatm to Ihe hetttt. A siMiflar fafctimny
occur with a Valsalva maneuver or after other kinds of strenuous activity (laughing, lifting heavy
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U.S. Naval Mi^t Surgeon's Manual
objects, ruming iipstakij'Hitt;.). Aortic steaosis with reduced left ventriculair omtput also
niiay lead ie iteiiting aftisr ekertion.
Cardiac arrhythmias causing ventricular rates below 35 to 40 or above 150 to 175 may
deefease fcardiac output over 50 percent and result in syncope. The most common arrhythmia is
the Stokes-Adams attack with a sudden complete A-V Mock. Tliese attacks usually give very
little warning and may occur with the patient in any position, including recumbency.
A hyperactive carotid sinus may lead to reflex cardiac slowing and/or a reflex fall in arterial
pressure, resulting in syncope. This may be initiated by turning the head to one side or by a
tight collar, although spontaneous attacks may also occur. The majority of cases occur in males
and nearly always begin in the upright position.
Workup and Digpogition of Aviators
Syncope is common and iftost of its cau^B, except for some of the cardiac disorders, are
fairly benign. Most syncope is "non-neurologic" in origin. A careful history is the most
important part of the workup. In addition to the usual physical examination, supine and
^ttofflhg bfedfl pressures and carifiae rhyftm should be assessed. Attempts to reproduce the
precise symptoms may be made, including 2 to 3 minutes of hyperventilation, Valsalva
maneuver, and carotid sinus massage (with an EKG monitor). Indicated laboratory studies
include a complete blood count, glucose tolerance test, and EKG with prolonged rhythm strip.
Occasionally, further workup with a 24-hour cardiac monitor and EEG may be indicated.
If an etiology is found and is benign, and if predisposing factors can be elindnatBd, an
aviator may be allowed to fly. If the etiology or abihty to eontrol the predisposing factors is in
dOTbti ^« avittor will generally need to be referred to the SBFS for evaluation of his flight
status. Often, a period of observation in a limited flight category (Service Group HI) wiU be
recommended in such cases.
Headache
Headaches are a nearly universal symptom. Although generally reflecting fatigue or tension,
on occasion a headache may represent a symptom of serious disease. As with most neurologic
problems, accurate diagnosis and treatment depend primarily on ehciting a detailed history, as
well as on knowledge of the clinical characteristics of the various headache syndromes. An
understanding of the basic mechanisms underlying headache is valuable, and this topic is
excellently covered in the classic text by Wolff.
7-6
NeortJogy
n
Migraine
Vascular headaches of the migraine type have been estimated to occur in roughly
5 to 10 percent of the general population, with women seeking medical attention ffidre often
than men. Onset of migraine is generally in the childhood or teenage years, but most frequently
becomes a proi^leas to the patient between the ages of 20 and 30. Frequency of attacks is
variable in different patients, and in any given patient it can change from year to year. Usually
the attacks occur once to several times per month, although they may be much less often.
Fifty percent' of afl attacks last under 12 koiirg, but the headache may last anywhere fitm one
hour to several days. Migraine has been divided into four categories depending on the clinical
picture: classical, common, compUeated, and cluster headaches.
About 10 percent of aU patients with migraine have the classical type. These are the patients
who have sharply defined visual and/or neurologic prodromes: scotomas, scintillations,
paresthesias of an extremity, or weakness of an extremity. These prodromes generally last
10 to 4S minutes and then subside with the onset of a throbbing unilateral headache I^iag
6 to 12 hours and often accontpanied by fiiorexia, nausea, and vomiting. Approximately-
80 percent of patients with classical migraine have a positive f amily history of migraine.
Common migraine afflicts about 80 percent of all patients with migraine. These patients do
( ) not have clear-cut prodromata but may have malaise, lethargy, or mild anorexia preceding the
headache. Although the headache is usually unilateral at the onset, it may be bilateral and often
becomes pner£fc«d. f&iMem often have naBtsea with m wilJiout vomting, as well as
photophobia md ganophobia. These headaches then tend to last one to several days* gradually
subsiding. They may terminate during sleep.
Complicated migraine is a rare form in which the neurologic prodrome (e.g., hemiplegia at a
hemisensory deficit) persists throu^out and beyond the headache phase. The neurtdja^ deficit
msy persist for days and is usually so alapming that an exfenave workup is undertaken. In most
instances recovery is complete, only to be followed by another attack at a future date.
Cluster headaches are an infrequent, but generally overdiagnosed, highly stereotyped
headache syndrome. These headaches occur predominantly in males (3:1), with the fiKst eluslst
oceurring in the teens or 20's. An extremely severe, unilateral, steady, and/or pulsating pain
develops quite abruptly in the region of the eye or temple. The attack lasts 15 to 90 minutes
(rarely longer) and then terminates rapi<fly , leaving the patient exhausted. During the attack the
eye is often bloodshot and tearing, the nose is blocked or running, and the face may be flushed.
Attacks most often occur after falling asleep or while dozing or relaxing, with such attacks
occurring usually once daily for several weeks.
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D-S. Naval Fli^t Surgeon's Manual
The treatoent for common and classical migraine that is most effective is the use of
vasjOeonstriGtots to abort or alleviate the headache phase. The ergotaminee in various forms are
widely used, and if taken at tfie eaidtiest wannng of a inigraifte attack are often highly effective.
The administration of ergotamine tartrate, 2 mg initially, followed by 1 to 2 mg at 30 minute
intervals until the headache is alleviated or until a total of 6 mg is taken, is a widely used
regimen. Maximum amounts of 6 mg per day or 10 to 12 mg per week should not be exceeded
hmmm of the risk of ergotism. For patients who have a great deal of nausea or vomiting,
s^fcjijip^ and suppository forms may be used. The um. of birth: eontrol plIlB should be
disiiontinued prior to the administration of ergotamines. Ergotamines should be avoided in
hypertensive patients and are contraindicated in pregnancy.
Miucle-Clontraction Headaches
. These headaches result from sustained contraction of the skeletal muscles of the head and
neck and are the most common type of headache encountered. The headaches are generally
described as a discomfort all over the head with a sensation of fiillness, pressure, or ti^tness.
Usually the main discomfort is in the occipital-nuchal area, and the neck feels tight or stiff. The
headache is nonpulsatile. It may begin at any time and is characteristically very persistent,
lasting weeks or months and rarely, years. These headaches are generally not accompanied by
visual, neurologic, or gastrointestinal symptoms. Aside from the finding of neck muscle
contraction or tender spots on the scalp, the neurologic examination is normd.
„. Evaluation depends on a careful history and examinationvE^flRattoitv£^#De>j^mptoms in
nonmedical terms is often helpful. The mainstay of drug treatment is aspiim, alone or in
combination with small amounts of codeine or a muscle relaxant Heat, massage, and physical
therapy help some patients.
Mixed Headaches
Mixed headache is the name gfren to those headaches which, as descrthedrby the patient,
have features of both vascular and muscle contraction headaches. This type of h^daehe occurs
frequently. Often there is a past history of fairly typical migraine attacks. However, over the
years, a more constant, dull headache has developed, punctuated by episodic attacks of severe
pain. Mixed headaehes may begin anytime and may develop in patients without a past migraine
history. The episodic severe headaches are generalized, throbbing, and accompanied by nausea,
vomiting,' photophobia, etc. There are usually no well-defined visual or neurologie Sf mptoms.
The cause of these headaches in most patients is tension, anxiety, and depression. Often the
patients deny depression or state they are depressed due to their headaches.
7-8
Neurology
The best response to treatment has been with a daily prophylactic-type medication. Best
results have been achieved with the tricycUc antidepressants given once daily at bedtime (e.g.,'
Elavil, Tofranil) in doses of 75 to 150 Cpmbililitlona of Ergotamines, barbiturate||qaD,f'
b^adonna have helped some patients (e,g„ Bellergal bid or tid). Ergotamines may be tisefiti|!|t^
the acute attacks of vascular headaches.
Headaches Related to Eyes, Ears, Nose, and Throat
Diseases of the eyes, ears, nose, and throat often cause headache or pain in the appropriate
end organ and suirounding region. However, in the absence of obvious disease of these organs,
they are rio'ely, if ever, a cause of headache.
The eyes should be checked for any inflammatory abnormality or obvious extraocular
muscle imbalance. Glaucoma should be considered in unexplained headaches in the over-30 age
group. Refractive errors, particularly hyperopia and astigmatism, occasionally cause headaches,
but there is usually a good history of temporal relationship t» eye use. '
WilliOttt obvious sinusitis, tooth abscess, otitis, etc., the ears, nose, and throat are alinosi
never a cause of headache.
-I
{ I Posttraumatic Headache
Aside from the expected headache following a head injury (which may last 1 to.^ weefcjs),
severe, chronic, contimious, or intermittent headaches may appear as the major sympteWt #1
two flcrstttfliunifftie syn4ro#SB. TJ^e headael^RW,mted with chronic subdural hematoma will he
discussed in the section on Head Trauuia which follows. 1
Chronic headaches a.ssociated with a variety of symptoms, such as dizziness, difficulty in
concentration, fatigability, nervousness, irritahility, insomnia, etc., make Up the so-called
"posttraumatic syndrome," In most patients the headaches have no special characteristics
except that ihey are usually referred to the side of injury. They frequently resemble
muscle-contraction h(;adaches. The vast majority of patients in whom the headaches persist or
recur for more than 2 to 6 months after the injury hme no intracranial, bony, ligamentous, or
other abnormality to account for the symptoms.
Treatment eonsisfc- of reassurance as to the absence of any serious damage and mild
analgesics as needed.
)
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U.S. Naval Flight Surgeon's Manual
Other Headaches
Although the above-described headaches account for well over 90 percent of all headaches,
the -posBibility of brain tuWiOr, subM^deKMia heihorrhage, or meningitis should be entertained in
patents isresentihg with the recent onset of headache. In thfe 1^66 of fever, meningitis eaii he-
ruled out. Subarachnoid hemorrhage is generally easily 'diagnosed % the classic history of a
sudden onset of very severe headache often accompanied by nausea, dizziness, alteration of
consciousness, or neurologic signs. The diagnosis is made by lumbar puncture and flie
demonstration of blood in the cerebrospinal fluid (CSF).
A small percentage of patients with brain tumor will present headaches pttot to the
development of neurologic signs or evidence of increased infracranial pJessure. The recent onset
of headaches in previously asymptomatic patients, particularly in the o'*ef-30 age ^6up, often
warrants further evaluation with an EEG and radioisotope brain scan. ■ '
Treatment and Disposition <tf Aviittdre
Althou^ headaches are not as common in pilote as in the general population, their
tteAttnfeiA 'iid^eW ^ome s^feeial" prdlilems. dsiMckl migraine with visuaI"and/or neurologic
symptoms is generally considered disqualifying. Other types of recurriiigii^adacheB inay be
disqualifying, if they occur with a frequency that might interfere with full operational ability, or
if they require frequent use of medication. Chronic medication use is also disqualifying.
AMAtom being treated for infrequent headaches should be grounded temporarily while on
medication and until the headache subsides. A lo#-iftmiify; tmist^-^'fracti'on headache
T^^ck'does not interfere with full phyldeal dSflity arid is tfdt ffi^tra^Sng need hot require
grounding. In any case, aviators with such mild headaches tHU ggA'^i'iE^ riot iffiek medical
attention. Difficult cases where flight status is uncertain are occasionaUy referred to the SBFS
after medical evaluation is completed.
•'>■
Head Trauma
There are an estimated one to three million head injuries annually resulting in
18,000 to 30,000 deaths and an even greater number of permanent sequelae. The majority' of
these injuries are due to automobile and motorcycle accidents. Currently, the military
expStience resembles the civihan, with a relatively low incidence of penetrating head injuries.
!•'' Ill .■ .
Complications of Head Trauma
Head injuries may cause scalp and skull wounds only, without damage to the CNS. In such
cases, scalp and skull injuries are significant if they result in secondary complications to the
brain, e.g., scalp infections leading to osteomyehtis and possibly meningitis or brain abscess.
7-10
Neurology
Skull fractures may or may not indicate brain injuries. In fatal head injuries, 20 to 30 per-
cent of autopsies reveal intact skuUs. On the other hand, many patients with skull fractures have
no serious or prolonged disturbance of cerebral function. Skull fractures may be signlfM^t
as: (1) an indication of the site and possible severity of a cerebral injury (as in epidural
hematoma, see below); (2) a cause of injury to meninges or brain by depressed fragments; (3) an
avenue for possible spread of infection; or (4) an explanation for cranial nerve palsies. Cranial
nerve injuries are seen most commonly in fractures involving the base of the skull. If the scalp is
laeerated over a fracture and the underlying meninges are torn, or if ari^itUi© plfiss^ ithrough
the posterior wall of a nasal sinus, menii|igitis, brain Edjaeess, or m ae^ Jtn^oj
Cerebrospinal fluid rhinorahea or; dtorrhea may develop and, if' ipersistentjv
Cerebral concussion is a clinical syndrome which appears following a blow to the head. It is
characterized by immediate and transient impairment of neural function, such as, alteration of
consciousness, disturbance of vision or equilibrium, or amnesia. Many concussed patiemtsjtiiiij
briefly unconscious. After regaining consciousness, recovery is usually rapid. Only an amnesia
for* #fis (period surrounding the head injury iFemsfes. Cortio^iCOTtosioBS with injuiy or death of
cortical tissue and extravasation of blood may occur in more serious head injuries, and often
such injuries are accompanied by longer periods of unconsciousness (15 to 30 minutes or more).
Cerebral lacerations with gross tearing of neural tissues occur in severe head injuries. Chnical'
manifestations depend on tfee site and extent of damaged brain tissue. •
Epidural hematomas are usually due to a fracture of the temporal or parietal skull with
laceration of the middle meningeal artery or a branch of it. The head injury may not have
caused loss of consciousness or may have caused only brief unconsciousness. A lucid interval of
minutes, hours, or 1 to 2 days occurs in about 25 percent of patients, and 75 percent of
epidural hematomas present within 48 houra. As the epidural hematoma enlarges^ fgttiilts ihig^
a gradually worsening heafdacfei^rvoiiiliMhgi o*sniilsim,(impairmeB^^ consciousness, .ipiilat^Jal
pupillary dilatation, contrdMecal hwaaiptfiSis or hemisensory loss, eonterfateral lbyip€treflexia,
and a Babinski sign.
Subdural hematomas are due to tearing of bridging veins and slfl.T^^4#B®tis bleecKng. AcMte.
subdurals usually result from severe head injuries. The clinical cause of acute snbdur^fej
essentially identical to that of epidural hematomas, with a progressive fall in tiie level of
consciousness with or without kteralizing signs. Ipslateral pupillary dilatatioiiis iiM»©ft*< •. '
Subacute and chronic subdurals (manifesting several days to several weeks following a head
injury) are usually evidenced by headache, drowsiness, and confusion or chalnge in personality,
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U.S. Naval Flight Surgeon's Manual
rather than by lateraUzing neurologic signs. Papilledema may be present. In some patients with
chronic guljitwJ heieii$ornftj no history of head injury or only a history of trivial injury can be
elicited* ■
Clinical Evaluation and Management
The category of minor head injuries includes those patients who never lost consciousness
due to the injury or who are conscious or rapidly regaining alertness at the time of evaluation.
L^'^^i^tion to ai history, these patients should have a thorough neurologic and general
eJEkiiiikatim, ^ith'. special attention to the gea^v skuU, and neck. Specific assessment of
alertness, rp&ponsivenessf and orientation should be madg.- iRopiUffry fetze and reactivity showld be
recorded as well as the vital signs. X-rays of the skuU and cervical spine should generally be
obtained, keeping in mind that the absence of abnormalities does not exclude the possibility of
CNS injury. Although the majority of patients in this category do not have any serious or
permanent injury to the nervous system, 24 to 48 hours of rest and observation are indicated in
ntostcAses.
The major head injury category includes those patients who have remained unconscious
since the time of injury, as well as those patients who had a lucid interval between the head
injury and time of evaluation. This group, although smaller than the previous one, is more likely
to hftve? sustained serious injury or to require surgical intervention for subdural or epidural
hematomas.
•5'' The initial management of craniocerebral trauma is the same as in any acute trauma: Res-
piratory distress and shock are the first problems treated. Prevention of hypoxia is especially
crucial to the management of head injury. The single most important measure is maintenance of
M: adequate airway. A general physical epc^inatibn to asseBH^assoeialed injuries is an important
plirt <of IftMst examination. The tympanic ml^mBranes and all areas of scalp ^nd ^uU should be
^antlil^d cat^fuUy. The initial neurologic exam shouldranelude at least the following: (1) level
of consciousness, (2) spontaneous movements, (3) response to verbal and painful stimulation,
(4) respirations, (5) pupillary size and r(-activity, (6) extraocular movements, and (7) deep
tendon and pathologic reflexes. It is important to record such an initial examination and to do
serial neurologic eafiUiraiations at intervals of ari hour or eveh more frequentiy, if the clinical
G^MUfSie^do warrants.
' i Ik
Coma or alteration of consciousness require prompt evaluation to determine if a surgically
treatable intracranial lesion is present. Lumbar puncture and electroencephalography are
generally not of value in the evaluation of acute head iifjury. Plain skuU X-rays and
echoencephalography may help detect an intracranial hematoma. Fluid replacement, beyond
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Neurology
actual blood loss, should be kepi lo a minimum ihitially, and GISS depressant drugs should be
avoided. *
The single most definitive diagnostic study to evaluate the possibility of subdural, epidural,
or other intracranial hematomas is cerebral angiography. Early experience suggests that
computerized tomography may also be useful diagnostically in the acute situation. In occasional
instances where the situation is life-threatening or where there appears to Be impending
herniation, exploratoi \ burr holes may be hfe-saving.
Sequelae of Head Injuries
The two most common sequelae of head injuries are posttraumatic epilepsy and th©
posttraumatic syndrome. '
Posttraumatic epilepsy complicates about 5 percent of dosed head injuries and ^mt
35 to 40 percent of open head injuries. Genersdly these occur in patients who have suffered
contusion or laceration of the cerebral cortex. In cases of pure concussion (without any focal
neurologic signs), seizures are not significantly moje frequent than in the general population.
The average interval between head injury and onset of seizures is about 9 months, with
90 to 95 percent of the risk over by IB to 24 months. The seizures which develop are always
focal or generalized major motor seizures, never petit mal. '. .-
A second, and often troublesome sequela, is the posttraumatic or postconcussive syndrome.
The most prominent feature of this syndrome is headache, accompanied by a variety of other
symptoms, inchiding dizziness, restlessness, fatigue, anxiety, insomnia, difficulty concentrating,
etc. Although these symptoms generally improve with time, they may persist for months to
years in some patients. After excluding treatable problems, patients are best handled wHfe
frequent reassUtance and mfld analgesics as needed.
Disposition of Aviators
Aviators who have suffered serious head injuries, such as skull fractures with penetration of
the dura or cerebral contusion vxUh focal neurologic abnormalities, are generally NPQ for
further flight status. The same is true for aviators who have had surgically treated intracranial
hematomas or any seizures following head injury. An aviator who has Stttfered a head inja^
with prolonged unconsciousness (30 to 60 minutes or more) should generally be observed lor
6 to 18 months prior to return to a flight status. In the case of simple concussion without any
neurologic signs (aside from a brief amne-tic period), an aviator may be returned to fli^t static
following an observation period of ftev(.>ral ilays. •
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U.S. Navd Flight Surgeon's Manual
Vertigo
The complaint of dizziness is encountered commonly. Few symptoms are rrlated to such a
variety of disorders, and few are more difficult for the patient to describe. For th( se reasons, a
careftil and precise history is important in evaluatii^ the dizzy patient. Four general areas
should be covered in the history; (1) the type of dizziness, (2) the eharacteristi(3s and patterns
of the symptoms, (3) the presence of associated auditory symptoms, and (4) the presence of
associated symptoms that surest neurologic disease.
True vertigo is a sensation of disorientation in space, accompanied by a sensation of motion
(rotary or spinning). In general, if there is no sensation of motion - that is, if the patient does
not have true vertigo - then the vestibular system (semicircular canals, utricle, ei^th cranial
nerve, and vestibular nuclei) is not involved, and other organ systems need to be considered.
The time of onset and the duration of the symptoms are important. Is it the first episode of
vertigo? Was it brought on or exacerbated by changes in position? Was the vertigo preceded by
infection, drug ingestion, or trauma? If a definite pattern is noted, the diagnosis may be
established without complicated investigation of the patient's other body systems.
Are there associated auditory symptoms? The most significant complaint is progressive,
unilateral hearing loss. Tinnitus may be present. Pulsatile tinnitus, a very common complaint,
often is simply perception of the heart beat. Careful hearing tests are an important part of the
evaluation of the patient with vertigo. Associated symptoms which suggest neurologic disease
should be inquired about specifically. These include diplopia, ttaresthesias, sensory loss, other
visual disturbances, hemiparesis, and impairment of speech or swallowing.
- The physical examination should include a careful neurologic examination. Often simulation
of the patient's symptoms is extremely helpfid in arriving at a diagnosis. Bedside maneuvers that
may be performed in an attempt to eKcit the patient's symptoms include (1) orthostatic
hypotension: measurement of blood pressure in supine position, then immediately on standing,
and at 3 minutes: (2) Valsalva maneuver; (3) unilateral carotid sinus stimulation for 15 seconds
(with ECG monitoring); (4) rotation of the head in each direction for 15 seconds (dizziness mav
result from "kinking" of a vertebral artery, cervicogenic dizziness, or a vestibular disorder);
(5) Walking and turning rapidly: this test reproduces dizzine® occurring with multisensory
deficits, apraxia of gait, and disorders of balance; (6) hyperventilation for 3 minutes; and (7) the
Nylen-Barany maneuver; the examiner carries the patient's head backward from a seated
position, so that it is hanging 45° below the horizontal and turned 45° to one side. Vertigo
accompanied by nystagmus indicates positional vertigo. If there is a lag between sliinulation and
onset of nystagmus and symptoms, and if the response tends to fatigue on repeating the test, it
7-14
Neurology
usually indicates benign positional vMigo (see Wow). If the onset of vertigo and nystagmus are
immediate and persistent on repeated testing, it usually indicates a central etiology.
Laboratory studies useful in evaluating vertigo include bithermal caloric testing to provide
information on the function of the vestibular apparatus. Audiometric studies are used to
evaluate lesions of the middle ear, labyrinth, and cochlear nerve, particularly in Meniere's
disorder and cerebellopontine angle tumors. Routine pure-toHfe audiometry indicates ifte
presence or absence of a hearing loss and may distinguish common causes (acoustic tfauma*
aging, otosclerosis) from specific cochlear and nerve disorders. More elaborate testing, including
the short increment sensitivity index (SISI), speech discrimination, Bekesy, and threshold tone
decay tests, improves the accuracy of diagnosis.
Vertigo accounts for only about one-tMrd of complainfe of dizzy patients. Following a
careM history and use of the simulation procedures outlined above, true vertigo can usually he
differentiated from syncopal disorders, seizures, and disequilibrium due to impaired balance
and hyperventilation.
When patients present with vertigo, it is important to distinguish between peripheral
(labyrinthine) abnormalities and those involving the cmtrd vesibolar connections. This
distinction can generally be made by the presence or absence of involvement of other areas of
the brain stem.
Peripheral Causes of Vertigo
Probably the most common cause of vertigo is Benign Positional Vertigo, which accounts
for about one-quarter of the presenting patients. The patient experiences a sensation of rotation
when he makes sudden head movements. The symptoms are Worse when the |tttetis lying
with his affected ear down. The episodes are brought on only with change in position, and the
vertigo, sometimes with nausea and vomiting, lasts less than 5 minutes. Between episodes there
are no symptoms. The cause is unknown. Diagnosis is based on the typical history and finding
the appropriate results on the Nylen-Barany maneuver. Caloric testing may reveal depressed
labyrinthine function in one ear. In most cases symptoms persist for several weeks, although
attacks may recur intermittentiy over a several-year period, with long, symptom-free intervals.
Acute labyrinthitis or vestibular neuronitis is defined as a single attack of spontaneous
verti^ lasting for hours or days. Occasionally such attacks follow trivial respiratory or other
infections. Symptoms of vertigo, nausea, and vomiting usually improve over 48 hour? but may
last for 1 to 2 weeks. Initially the patient looks acutely ill, pale and diaphoretic, and resists head
-motion. Nystagmus always accompanies the vertigo. As recovery occurs, the patient may feel
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tJ.Si Naval Flight Surgeon's Manual
**^f£ |ia|iaci?i' im. UBifeady for weeks or Birarths. This is due to unilateral impairment of
labyrinthine function, present in about half the patients. Hearing is not impaired.
Meniere's disorder accounts for only 3 to 5 percent of all dizziness and about 10 percent of
vertigo. It is widely overdiagnosed. It consists of recurrent attacks of vertigo, accompanied by
hearing loss and tinnitus which may precede the first episode of vertigo. Patients may complain
Otia filJliafss in the ears and san^etpaes complain of discomfort due to loud noises (dve to
rewuitaiewt). Attacks of vertigo last from hours to days. The frequency of attacks iajii^y
variable. In most patients hearing loss is unilateral and may be severe,- Many patients develop
chronic impairment of vestibular function leading to a constant sensation of imbalance.
Diagnosis depends on the characteristic history and audiometric findings (low-frequency hearing
loss, poor speech discrimination, and recruitment).
. I%ma damage to the labyrinths may be caused by aminoglyteoside antibiotics
(Stt©ptt>|i(yeiii, Gentamycin), as well as other drugs. Tinnitus, hearing loss, or VBJtigQ may be
the initial symptom, along with impairment of balance, nausea, and vomiting. Vertigo can
continue for days or weeks and then be followed by loss of balance and blurring of vision on
motion, because of loss of vestibulo-ocular reflexes. Diagnosis is based on the history of use of
atWoxio dbip, followed by the characteristic eUnical features. Caloric tests usually reveal severe
impaiTment of labyrinthine function.
Other peripheral causes of vertigo include head trauma, presumably due to dislocation of
the otoliths from the macula of the utricle. Cervicogeriic vertigo is thought to be caused by
extensive input to the brainstem vestibular system from the musculature of the cervical region,
gS> #«t cervical spondylosis or even severe muscle contractiDn may result m vertigo. Otitis media
flP^ hjp^Kyj^oidism can also occasionally result in vertigo.
Treatment of vertigo due to most peripheral vestibular causes is similar. The patients are
treated with bed rest (if severe), Meclizine, 25 mg four times daily, Atropine tablets, 0.4 mg
subUngually at onset of attack, and Tigan or Compazine suppositories. Valium, 5 mg orally, may
help «5ontr0l the anxiety that usually accompanies vertigo. Soft cervical collars may help
patients with positional vertigo or cervicogenic vertigo.
Central Causes of Vertigo
Cerebrovascular disease can cause vertigo when vertebrobasilar artery ischemia damages the
vestibular nuclei or their connections. However, vertigo is not hkely to be due to stroke in the
absffice of other neurologic symptoms or signs.
O
o
o
7-16
Neurology
Multiple sclerosis accounts for only 5 to 10 percent of acute vertigo in patients under
age 40. This presentation of multipk sclerosis is far less mmmmi lkm onset irflii optic neuritis
or paresthesias.
Cerebellopontine angle tumors are a rare cause of vertigo, but must be considered if they are
to be diagnosed at an early, more treatable stage. These tumors most commonly occur in
middle-age and present with vague unsteadiness that progresses over several years. Vertigo, w^hen
present, may be of the "ceftW' ' pesitiond tj^pe.^ OaJt^s iliarely does acute spontaneous
occur. On caloric testing the*^ is a Bi#rkedly. deereased response on the affected side.
Audiometry suggests a retrocochlear lesion, with rapid tone decay and a Type III or IV B^ek^Sfi
pattern. X-rays of the petrous bones show erosion of the affected internal auditory canal.
Viral infections rarely cause vertigo except when herpes zoster affects the eighth mrvW, In
the Ramsay -Hunt Syndr«»n#i facial paralysis, ypttifa, and,hewnf loss occur with herpetic
vesicular lesions in the external auditory canal.
Disposition of Aviators
As a general rule, a complaint of vertigo requires that aviators be grounded for thorough
evaluation. With the exception of a few causes of vertigo which are unhkely to cause recurrent
episodes, e.g., acute labyrinthitis, otitis media, head trauma, etc., a diagnosis of niOBt of the
problems described j^we will lead to permanent disqiialificatipn. As always, pilots shoiild
remain grounded whfle ©n treatment with any njedioatioti. Jji awf ia#t«WBlv; 6 months of
observation are iiidicated after completion of treatment to allow f or epittplete »t8©iation: ©f fil<
symptomatology.
Menin^tis
Most patients with meningitis present with fever, stiff neck, lethargy, confusion, headache,
and vomiting. Some patients become acutely iU within 24 hours, while others may have
antecedent respiratory symptoms, headache, otitis media, sore throat, or cough for 1 to 7 days.
Other symptoms of bacterial meningil^ ate backache, weakness, dizzuiess, photophoMa, and
myalgias.
On physical examination most patients demonstrate signs of meningeal irritation, such as
stiff neck and positive Kernig or Brudzinski signs along with fever. A petechial skin rash is rare
in meningitis caused by bacteria other than meningococci, unless bacterial endocarditis is
present. The level of conseiousness in most patients varies from confusion and mild lethargy to
deep coma. Although increased intracranial pressure is common, papilledema is rare, unless
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U.S. Naval Flight Surgeon's Manual
there is an underlying brain abscess, subdural empyema, or venous sinus thrombosis. In
approximately 50 percent of the patients, neurologic signs develop during the course of
meningitis, such as seizures, cranial nerve palsies, or hemiparesis. These proWdirris ^ c^ftetl
With the exception of epidemics of meningococcal meningitis which are usually confined to
miUtary camps or schools, bacterial meningitis occurs sporadically, usually in a setting of some
aestrtsteted'iifeeaSeV 'The three m<ist (K)(ttiA6n' inicro'6rgaiWns' Causing meningitis, aside from
Mycobacterium tuberculosis, are Diplococcus pneumoniae. Neisseria meningitidis, and
Hemophihjs influenzae. The meningitis caused by H. influenztte iS lincommoii #ter' 8ge 6 and
rare after age 12.
More extensive discussion of the pathogenic organisms and comphcations of bacterial
mm^a0s im be found in any major textbook of Mii^difcifee. KerftfiM ^damage to the nervous
Sjr^em ocmwa in IQ to 20 percent of patienla and is most common g^m ptteumococcal
meningitis in adults and H. influenzae meningitis in children. Deafness is the most common
sequel; hemiparesis, seizure disorders, and dementia are occasionally seen^ " '
iom of badterial meningitis is not difi^^t, as long as a high index of suspicion is
iv I4 4h0nid fee eensiieMd -in every patient witH a'Wgfdry if -kn upper respiratory
by vowitifflg, leth^^ h©adachfefV€GAftiii«tt, ii3r«ittAFMdt.'The CSF should
be examined in every patient with evidence of meningeal irritation. Papilledema fe not a
contraindication to lumbar puncture in patients in whom the diagnosis of meningitis is
suspected. The CSF pressure is usually elevated, and the fluid may appear clear, slightly turbid,
or grossly purulent. The fluid should be centrifuged immediately and the sediment gram-stained
and cultured on blood and chocolate agar under increased CO2 tension and anaerobically in
thiogly collate. The number of cells Varies ftbm 100 to 100,000 per pubic milHmeter. Initially
polymorphonuclear leukocytes predondnate; tliese me replaced by lymphocytes as the
inflammatory process progresses.
A low CSF sugar is the hallmark of bacterial meningitis and distinguishes it from viral
meningitides. Usually the value is below 40 mg percent and may be close to zero. The ratio of
blood sugar, which should always be obtained at the time of lumbar puncture, to CSP'sulM-is
normally 1.5 to 1 , and larger ratios are ako su^ect The protein content is generally elevated
and may be as high as 800 mg percent.
7-18
' ' Neurology ' ^ "
Blood cultures should be obtained routinely in patients suspected of having meningitis, sin^
they are positive in about 50 percent oi cases.
Treatment
Penicillin is the drug of choice for pneumococcal and meningococcal meningitis and should
be administered in a dosage of 10 to 20 million units a day, preferably in four divided doses.
For patients sensitive to penicillin, chloramphemical in dosage of 4.0 to 6.0 gm per day should
be used. The same appUes to adults with undiagnosed bacterial meningitis pending specific
culture results. In the absence of extrameningeal foci, 10 days of treatment is gesnerajly
adequate. The GSF should he reexamined etery 24,t®.48 hottrsMt4a%,thf^HFffli|«8©v<i^,fift
less frequent intervals. If there is evidence of increased intracranial pressure, dexamethasone,
10 mg I.V. initially, then 4 mg every 6 hours, can be used once antibiotic treatment is initiated.
Other supportive treatment includes parenteral fluids and anticQnvulsants if needed.
In Gases of meningococcal meningitis, the meiiaa H&teteR cftilfa«Efe fflijjctol WiUlacts is quite
low and should not induce the hysteria which often follows diagnosis of a case. I^f^Slftion
gttjups such as mffiftoy Mges or schools, sufiteMteiides may be used in contacts, but only when
the causative organism is susceptible. There are sulfonamide-resistant Group A, B, C, and
Y strains, and for this reason, peniciUin is the drug of choice in treatment of meningitis.
Penicillin unfortunately does not eliminate the carrier state in many cases, even in therapeutic
doses. Both Rifampin (600 mg daily for 5 days) or MinocycHne (200 mg, then IpOmg twi(^i
daily for 5 days) singly, sequentiaUty, % m^'^'^^%^^^f^^.¥^^^^^^^^^^
eradication of caijier states; these two drugs should nev^r be used for treatment of actual cases
of meningococcal meningitis.
Recently, meningococcal vaccines for Group A and G hAJee been devfelqped and used
prophylactically in military recruits, and this promises to bieltbe best approach to preveliion of
meningococcal disease. Vaccines for Oth^ bacterial meningitides have not been developed.
Seizures
LennoiE, W., & Lennox, M. %ffejirr* Boston: Little, Brown, and Co., 1960.
Schmidt, RJ., & Wilder, B.J. Epilepsy. Contemporary Neurology Series. Philadelphia: Davis, 1968.
Solomon, G.E., & Plum, F. Ciim^l management of seizures. Philadelphia: W.B. Saunders Co., 1976.
Syncope
Friedberg, C.K. Syncope: Pathological physiology: Differential diagnosis and treatment. Modern Concepts of
Cardiovascular Disease, 1971, 40, 55-60.
7-19
U.S. Naval Flight Surgeon's Manual
Lee, J.E., Killip, T., Ill, & Plum, F. Episodic nnconsciousnesB. In J.A. Barondess (Ed.), Diagnostic approaches to
presembtg-^n^omet^Bvi^oTe: Williams & Wilkins, 19TI, X33-lj^7.
Wayne, H.H. Syncope. Physiological considerations and an analysis of the clinical characteristics in 510 patients.
American Journal of Medicine, 1961, 30, 418.
Headache
Friedman, A,P. Research and clinical studies in headache. Baltimore: Williams & WUkins, 1967.
Lance, J.W. The mechanitm and nutnagement of headache. London: Butterworth, 1969.
Wolff, H.G. Headache and other head pain (3rd ed.). Fairlawn, N J.; Oxford Univeisity Press, 1972.
Head Trauma
DeJesuB, P.V., & Poser, CM. Stibduial hematomas: A efinluopatiholog^ ielutFy of 100 cases. Posigmdmte
Medicine, 1968,44^,172-177.
Evans, J.P. Acute trauma to the head. Fundamentals of management. Postgraduate Medicine, 1966, 39, 27-30.
Gallagher, J.P., & Browder, EJ. Extradural hematoma: Experience with 167 patients. /ournof of Neurosurgery,
1968,29,1.
Kiay* UMM,tt iGe*E, T»A., & Laasman, L.P. Brain trauma and the postconcus^onal ^ntbronie. Lancet, 1971, 2,
Walker, A.E., Caveness, W.F:^ * QfitcMt^, M. (Eds.), bte effeisli ofhead bijuryj %riiigfield, Ill»« Titmm,
1969. r ■ , r
ifeHigb'
Bi-achman, D.A. Episodic vertigo. In H. Ck>nn (Ed.), Current therapy. Philadelphia: W.B. Saunders Co., 1974.
lifitehMalni,'D,A., & Bart, C.S. An approach to the dizzy patient Neurology, 1972, 22, 323ff.
HaMson, M.S., & Ozashino^er, C. Positional vertigo: Aetiology and clinical significance. Brain, 1972, 95, 369.
Meningitis
4i!tenrt«in^ J(t.S^ .jS^l R., Zimmerly, J.G., Wyle, F.A., Schneider, H,, & Harkins, C. Prevention of
meningococcal disease by Group C polysaccharide vaccine. New En^nd Journal of Medicine, 1970, Si82,
417. . - . ■
Feldman, H.A. Meningococcal infections. In G.H. Stollerman (Ed.), Advances in internal medicine, (Vol 18).
Chicago: Year Book Medical Publishers, 1972, 117-140,
Pettrsdorf, R.G. Bacterial meningitis. In P.B. Be^tt'& W-'MeDermott (Eds.), Textbook of medicine (Hth ed.).
Philadelphia: W.B. Saunders Co., 1975.
7-20
o
o
t
CHAPTER 8
OTORHINOLARYNGOLOGY
Mtroductioti •
Section I: Clinical ENT
Otology
Rhinology
Examination of the Mouth and Pharynx
Laj*yiig6logy
Section 11: Audiology
The Physics of Sound
Measurement of Hearing
Interpretation of Hearing Tests
Section HI: The Navy Hesuring Conservation Program (HCP)
Introduction
Implementation of HCP
Noise Measurement and Exposure Analysis
Audiometry in the HCP
Hearing Protectors
References
Bibliography
Appendix 8-A. Minimal E»|uipirtent f or INT Exatttination and Treatment Units
Appendix 8-B. Model Instraction for Establishing Noise Control and Hearing Conservation
Program
Introduction
Otorhinolaryngology (ENT) faces the same problems in military, iwlation mediffliie #at are
found in civiUatt ittfeffieid pMe&&e, but the problems are compounded b^ (1) the exceptional
environmental conditions of aviation and (2) the fact that some of the symptoms experienced
may degrade flight performance to the point where the safety both of the aviator and his
passengers may be threatened. The exceptional environmental conditions include rapid pressure
changes, high ambient noise levels, and unusual linear fliid aU^llir' «6^1teratft>ilS. Th^
environmental conditions can eUcit epiMtfd^ of pain, vertigo, disequihbrium, and nausea. Th^
may also introduce communication problems through tmipmmr or permanent impairment of
auditory fiinction. In addition, these effects can be sudden in onset in apparentiy normal
individuals.
8-1
U.S. Naval Wli^t Siu^oa's Manufil
This chapter describes chnical ENT issues, audiology, artd the Navy Hearing Conservation
Program. Fli^t Surgeons may find themselves at long distances from medical facilities when
ENT problems arise, or they may have to care for patients until they can get an appointment at
the nearest facility; therefore, this chapter is intended to assist the physician with common
chnical problems.
Due to the constant problem with acoustic trauma in aviation and aboard Navy ships, the
evaluation md conservation of hearing is an importatit part of the Fh^t Surgeon's
responsibihty. He is responsible, in part, for administering the Navy Hearing Conservation
Program .
The material in this chapter is closely allied with that presented in Chapter 3, Vestibular
Function, which discusses illusions and disorientation effects which can result as the vestibular
system reacts to the unique stresses of aviation.
SECTION I:
CLINICAL ENT
Otology
The Management of External Ear Problems
Hematomas. Trauma to the auricle may cause hemorrhage beneath the perichondrium, most
often on the superior lateral surface, resulting in a hematoma. Left untreated, the slow
absorption of blood, loss of nourishment to the cartilage, and infection may lead to a deformed
auricle or "cauUflower" ear.
Management may take two forms. In the early stages, aspiration of the blood using sterile
techuique with a large 14-gauge needle is recommended by many phyacians. A pressure dressing
is then applied. For large, chronic, or recurrent hematomas^ incision and drainage are
recommended. The entire ear is prepared with Betadine, and under local Xylocaitie anesth^a, a
large curving incision is made through the skin of the scaphoid fossa following the curvature of
the helix. The hematoma is then evacuated using sterile technique. In some chronic or recurrent
cases, instead of blood there is only xanthochromic fluid. Some surgeons advise curettement of
the cyst walls. A thin rubber drain is inserted the Im^ of the sac or cyst and then withdrawn
over the next two or three days. Fine nylon or silk interrupted sutures about one centimeter
apart are used for closure of the incision, and a pressure dressing is apphed.
8-2
Otoihinolaryngology
The Plight Surgeon is cautioned that aspiration of aural hematomas without meticulous
attention to sterile technique is an invitation to disaster heoswise of the excellent culture
medium contained therein.
Perichondritis and Chondfit^ of the Anrteh. The ^read el infee^oiij most often after
trauma, to the perichondrium results in a painful,' hot celluhtis of the piima with hrawny edema.
Aggressive systemic antihiotic therapy aptl warm, wet compresses are the treatment of choice,
along with repeated cl'^-aning of the wound. If chondritis develops, the infected area must be
opened and drained witi. excision of infected cartilage. For these infections, cultures should be
made for proper drug therapy.
Lacerations. The basic principles of handling a laceration of the auricle are to avoid
excessive debridement, approximate the Cartilage with perichondria! sutures on both sides, use
white silk or cotton for buried sutures on the thin lateral surface, and use good splinting with a
pressure dressing. Even though a portion of the ear may look nonviable, it is usually best to
clean, approximate, splint, and ihen wait for demarkation before final debridement. Through
and through sutures tied lightly over cotton roUs, etc., may be used for splinting as well as the
pressure dressing. Exposed cartilage or sukcutaneous tissue should be covered with fine mesh
gauze impregnated with an antibiotic ointment. Ad^^pate antibiotic coverage is strongly
recommended.
Ear Dressing Procedure. The purpose of the dressing is to splint, protect, and absorb
drainage from the ear with maximum comfort to the patient. It must also resist movement or
displacement.
The bandage material most commonly used is a supportive pad behind the ear, a fluff
dressing of loose gauze or mechanic's waste, and a support covering of the dressing with material
like KhngC^) or Kerlix(^) elastic or stretch gauze.
First, two or threfe 4 x 4-inch pads are folded together in half, and Aen a "C" shape is cut
out of the center that will It behtlil aR(S*Wtoad t^^ ear (FigMre 8-1). Next, the entire ear is
covered with two or three iiaAes of fluff dressir:g or mechanic's waste (Figure 8-2). If splinting
of the pinna contours is important, as in lacerations, this can be accomplished by careful
insertion of ointment-impregnated cotton in the grooves of the scaphoid fossa, canal meatus,
and concha.
The external bandage of an elastic or stretch gauze usually b^ns on the forehead and is
always wrapped from the front to the back of the ear (Figure 8-S). To keep the dressing out of
8-3
U.S. Naval Flight Surgeon's Manual
the patient's eyes, two pieces of umbilical tape or thin gauze are laid vertically on both sides of
the forehead. The stretch gauze is wrapped first across the center of the fluff, across the lower
occiput, above the opposite ear, and then repeated below and above the first wrap, resulting in ^
football-Uke appearance (Figure 8-4). The forehead tapes are now tied and tape strips apphed to
hold the gauze in position, using intermittent applications about six inches in length
(Figure 8-5).
Figure 8-1. Ear dressing procedure, Step 1.
Figure 8-2. ^Eai <lfessing procedure, Step 2.
84
Otoifainolaiyngologf
U.S. Nav^ flight Swj^ojqj's Manual
Foreign Bodies in the External Canal. Anything that will fit has been found in the external
auditory canal. Some of the foreign bodies are inert and cause no problems or symptoms, but
most commonly they produce a canal blockage with mild decrease in hearing, itching, infection,
md drainage or even a cough, mediated through presrfre oii fj^twig of th^^tenth cranial nerve
(Arnold's nerve). ~
Removal of round objects is most difficult, and it is best accomplished with a fine, blunt,
right angle hook that can be inserted past and behind the object. Special cup or serrate jaw
forcepis can also be used. Hard, sharp, and large objects should be soft^ed, if pos^le, and
removed with care, protecting the canal from trauma and bleeding. Compressed strips of
Gelfoam may be tried on sharp corners. Friable or adherent material may require loosening or
dissolution before removal. Debrox (carbamide peroxide) works well in most cases. A fine
stream of water, two percent acetic acid in water, or alcohol is used for irrigation and directed
under direct vision and controlled pressure. Hydroscopic objects such as corn or peas may swell
if saturated with water, therefore, alcohol irrigation or forcep/hook removal is recoramended.
Live insects should be killed rapidly by flooding of the canal with ether, alcohol, or oil and then
removed with forceps. After the object has been removed, the canal should be suction-cleaned
or wiped dry and eardrops or ointments applied for treatment of any possible tissue trauma or
infection.
ExterM. Otitis^ The lining of the extemisd auditory canal, including the outer surface of the
tympanic membrane, is facial skin and, therefore, susceptible to the same infections as the face.
The outer third, surrounded by an incomplete ring of cartilage, contains hairs and sebaceous and
ceruminous glands. Infection may take place in any of these structures, most commonly as a
furuncle. The fissures of Santorini in the floor of the external meatus may allow for spread of
infection into the soft tissues of the periaurie\ilar region.
Treatment of furuncles consists of application of dry heat to the external ear and direct
application of topical antibiotic solution or ointment to the inflamed area. If the furuncle
points, the top should be removed by suction or needle to allow for drainage. Diffuse swelling
and/or cellulitis lecpiire systemic antibiotics. Recurrent furuncles may be conltolled by
applications of CresatinC^), Betadine, or antibiotic ointment daily to the meatus region.
The most common causes of infections in the external auditory canal are maceration of the
skin from water or other fluid drainage and trauma, often self-infUeted, when trying to scratch
or dean wax from the canal. The canal becomes inflamed and may begin vter^ep, and there
may be mild pain on movement of the pinna. Predominant causative organisms are
Staphlococcus aureus and Pseudomonas. Progress of the i|]^||njinii,^on leads to variable degrees
of canal swelling, fever, severe pain, and often trismus.
8-6
Otorhinol^iigplpgy
Meticulous cleaning of the entire canal is the single, most important form of treatment. The
canal should be gently suctioned and cleared of visible debris, and the inflamed tissue should be
wiped with antibiotic drops or two percent acetic acid solution. Carbamide peroxide (Debrox)
may Ids' needed; ife&er© k hirf ®r thi^fc 4 Bttwdimotion!; and wiping of^#ito#lff<iwdlift
canals should be velEf gentle with attention to the direction ©f the^c^al and'H^teice^st^i -iie
tympanic membranei. A vref cotton canal wick about three-quarters to one inch long is
recommended for use in all cases with diffuse swelling of the canal. Burow's solution (1:10) is
an excellent astringent-type medication, but any of the antibiotic -cortisone otic preparations
can be used on the wick. The wick should be large enough to be snug and in contact with the
inflamed tissues. It is kept wet and removed after 24 hours. Antibiotic drops themselves create
debris, so the canal should be cleaned suid a new wick inserted Aljly Uiftil the gwelling has
maffise^y tesolyed* A patient should never be given a bottle of drops and sent off on a course of
self-treatment. Patients with adenopathy and celluUtis should be treated with sygternic
antibiotics, and the pain can be controlled with a strong anodyne.
Otomycosis of the external canal constitutes less than five percent of all cases of external
otitis, but it~49*«»j»»««*^*sg0^eia^ of airtibioi^@L,dr#f 8*ai^^
canal. The most common causative agents are AspergiUus spedem^^ Monilia. When the canal is
not inflamed and the infection is mostly a saprophytic fungal growth, the cerumen, debris, and
fungal growth are suctioned out followed by flushing of the canal with alcohol and thorough
drying. When the canal is inflamed, gentle, meticulous suction is the first step in treatment.
Mycostatin or Fungiaone cream is apphed for Candida infections. Aspergillus species may
require treatment with two percent Gentian Violet in, S5 (percent alcohol, or gii&^eicmt4hiytiiol
fohition in ethyl alcohol, or perhaps best of all, a 25 percent m cresyl acetate (Cresatin)
solution. In chronic ottorhea, the underlying pathology must be controlled, , or .the fungn^^jKill
return. This could necessitate performance of a radical mastoidectomy.
The Middle Ear
Anatomy. The part of the ear which is perhaps of greatest importance in aviation is the
Eustachian tube. It is approximately 37 mm long and connects the middle ear with the
nasopharyiix. T^e lateral or tympanic third of the tube Is Botty, iie medial or pharyngeal
portion is cartilaginous. The course of the tube is forward, downward, and inward from the ear,
opening into the nasopharynx aBout 15 mm lower than the tympanic opening in adults. It lies
just posterior to the inferior nasal concha. The cartilaginous and bony portions meet at an
obtuse angle in the narrowest portion of the tube. The osseous tympanic orifice is open, but the
cartilaginous tube is a closed, dit-iike eaiSly. E must be dpen^ By acts of "^iSj^bwing or
yawning that contract the tenser and levalor veil palatini muScles or by direct air fi^emire.
8-7
U.S. NavsJ Flight Stti-geoh's Manual
Eustachian Tube Dysfunction. Edema or tissue hypertrophy in or about the pharyngeal
orifice of the Eustachian tube from infections, inflammations, or allergy is the most common
cause of acute dysfunction. Chronic dysfunction is usually associated with anatomic
abttormalities, such as searring and cftwiMfic disease processes^ With an acute,- unexplafeed,
unilateral dysfunction, especiidly in the older age gFiim|)v one should always look diligently for
tumor in the nasopharynx. <
Symptoms of Eustachian lube dysfunction are generally a fuUness in the ear, mild
intermittent discomfort or pain, and a mUd decrease in hearing. The tympanic membrane shows
iome retraction with either a normal appearanfce or sUght hyperemia of the vascular strip. The
short process of the malleus is prominent or foreshortened, and the malleus may angle more
posteriorly than usual. In chronic cases, there is t "dimpte'* or retraction of the pars flaceida.
In the acute disease, treatment is directed toward control of any infection in the
nasopharynx, and a decongestant with an antihistamine is recommended. Stubborn conditions,
with no obvious etiology and no previous history, often respond to two wfeks of nasal
insufflation of Turbinaire and occasional politzerization. Cases that develop after an initial ear
hloek Of ear inffecfaoil and legist ottier eongervative Ueatment, ©icGMonally respoftd to
ventilation tube insertion for a minimum of three months. This can also be effective in some
longstanding chronic cases. In children and selected resistent cases in adults, an adenoidectomy
may be advisable.
Direct Trmma. Direct trauma can occur from the increase in air or fluid pressure in the ear
canal caused by a slap to the side of the head, falling off water skis, improper water entry during
a dive, ear blocks while flying, ear squeeze during SCUBA, or improper irrigation of the ear
canal. This may result in rupture of the tympanic membrane, laceration of the canal, and
occasionally, ossicular disarticulation or subluxation of the stapes. There may be some bleeding,
often marked tinnitus, and occasional vertigo and hearing loss, depending on the degree and
location of the injury. Infection often results when foreign material, especially water, is forced
into the middle ear through a ruptured tympanic membrane. Treatment should consist of
suction clearing, antibiotic coverage for five to seven days, and a base hne audiogram. Clean,
traumatic perforations usually heal within three weeks, but the patient must avoid any
significant barometric pressure changes as the perforation nears closure, and at no time should
water or other fluids be allowed in the ear.
Bamtrauma. Aerotitis media occurs rather frequently in the aviation comtnunitf and is
directly related to the function of the Eustachian tube in equalizing the pressure between the
atmosphere and the middle ear space. The tympanic end of the Eustachian tube is bony and
8-8
Otorhinolaryngology
usually open, whereas the pharyngeal end is cartilaginous, slit-like, "arid closed, acting like a
one-way flutter valve. Opening of the Eustachian tube occurs with the contraction of the levator
and tensor veli palatini muscles during acts of chewing, swallowing, or yawning. As one ascends
to altitude, the outside pressure decreases, and the greater middle ear pressure forces open the
"flutter valve," pharyngeal end oi til© Eustachian tuhe every 400 to 500 feet to sikmt.
35,000 feet, and then every 100 feet thereafter. During descent, the collapsed, closed,
pharyngeal eaid of the Eustachian tube prevents air from entering the tube. "Eh© itiCffiMsing
relative negative pressure in the middle ear further holds the soft tissues together, and muscular
(active) opening of the Eustachian tube must be accomplished before the differential pressure
reaches 80 or 90 mm Hg. Once this magnitude of differential is established, muscular action
cannot overcome the suction effect on the closed Eustachian tube, and the tube is said to be
"locked." This relative negative pressttre not oiily retraet& the tympanic membrane but pulls on
the delicate mucosal lining, leading to effusion and hemorrhage. Pain may be severe, with nausea
and occasionally vertigo. An occasional rupture of the tympanic mpubrftfte h^ been. seen, and
some airmen have developed shock or syncope.
OtoSGopic presentations vary greatly, but they can range from a rfetractipm- of the tympanic
membrane with the classic backward displacement of the maUeus, a prominent short process,
and anterior and posterior folds, to hyperemia or hemorrhages in the tympanic membrane.
There may also be varying amounts of serous and bloody fluid visible behind the membrane.
Active treatment is directed toward equahzation of pressure, relief of pain, and prevention
or treatment of ilifeelions in the ear, Eustachian tube, dr nasopharynx. In an iii«^a#E or
low-pressure chamber, descent should be stopped, and, if possiblei there should be a return to a
higher altitude where equalization can be attempted using the Valsalva maneuver or Pohtzer
method. Descent should then be gradual, if possible. Middle ear mflation by the physician
should be done only if a negative pressure appears to remain on the ground and there is pain
present. Caution should be exercised if there is an upper respiratory infection present. Oral
decongestants may be helpful and arfe recommended, but the effect of afitfeistamines is
questionable. In cases of tfiick effusion and poor Eustachian tube function or inabihty to
Vdsalva, daily or every other day politzerization or tubal insufflation may be in order.
Persistent serous fluid may be removed by needle aspiration, but thick mucoid or organized
blood must be removed by myringotomy if it has not cleared after one or two weeks of
intensive therapy. Antibiotics are used only when infection is present in the upper respiratory
region or develops during treatment-
"fatsahfU Mmem&r. The proeedure for self- or mechanical inflation of the middle ear
space is termed the Valsalva maneuver. It has been frequently observed in young student pilots
8-9
U.S. Naval Hight Surgeon's Manual
and mrmem receiving earblocks in the low-pressure chamber or in flight during rapid descent,
that they were unable to perform a proper Valsalva, frequently because they did not know the
correct technique or were trying too hard. Several physiological conditions make the Valsalva
maneuver more difficult. They are flexing the head or the chest, twisting the head to one side,
pressure on the jugular vein, and being in the prone position.
The Valsalva maneuver requires the nose and mouth to be closed and the vocal cords open.
Air pressure is then forced into the nose and nasopharynx forcing open the Eustachian tube and
increasing the pressure in the middle ear space* This can be observed as a bulging of the
tympanic membrane, especially in the posterior superior quadrant.
The most frequently observed problems with the students were fear that dley would damage
' or ruptoire their eardrums, closing the vocal cords when they build up pressure like in the
M-1 maneuver, and straining so hard that marked venous congestion in the head further prevents
opening of the Eustachian tube.
Atthou^ it fe possible to luptute the tympanic membrane when it is abnormally weak from
previous disease, simple inflation done properly has little danger. Repeated overinflation does
carry some risk and is discussed under politzerization and round window rupture.
One of the best methods to prevent vocal cord closure is to instruct the patient or airman to
close his nose with his fingers and then attempt to blow his fingers off his nose, causing the nose
to bulge from the pressure. The buildup of pressure should be rapid and sustained no longer
than 1 to 1.5 seconds to prevent the venous congestion that reduces the efficiency of
Eustachian tube function.
Should the Flight Surgeon fail to see any movement of the tympanic membrane when he is
evaluating the patient for Valsalva, he should then look for the small, quick retraction
iBOvement of flie Toyrdiee maneuver, accompUshed by closing the nose and swsdlowing. If a
Toynbee is present and the airman feels pressure in his ears during Valsalva, has no sign of ear
disease, and no history of problems with pressure changes, he usually can be quahfied for
aviation. The best evaluation for candidates is, of course, the low-pressure chamber or an actual
unpressurized flight with rapid descent. Difficulty with pressure equalization during SCUBA is
often a poor prognosis for aviation.
Politzerization. Politzerization is the mechanical inflation of the middle ear usually required
tor treatment of acute ear and sinus blocks, chronic Eustachian tube dysfunction, or middle ear
disease. To perform this procedure, one needs a source of pressure, either an air pump or rubber
bag, with a one-way valve. For the air pump, it is most important to have variable control of the
8-10
Otorhinolaryngology
pressure and a pressure gauge, if possible. Most pressure/vacuum units in the Navy have a
pressure gauge calibrated in pounds per square inch. If no gauge is present, the starting pressure
should just be sufficient to blow off a lightly appUed finger. Wheti fi|fre|gare gauge is available,
initial attempts should be done with ten pouiids per square inch or less. To seal and deliver the
pressure into the nose, an olive tip of metal, hard rubber, or glass is the most efficient. This tip
may be attached to an atomizer if smoke or mist is desired for diagnostic or therapeutic reasons.
If the patient has a very thin tympanic membrane, lower pressure must be tried first. An
explanation to the patient is important to assure cooperation and prevent sudden movements
that could injure the nose.
The first attempt at politzerization should be done by inserting the olive tip into a nostril,
getting a good seal but not striking the vestibule or septal walls. The opposite naris is occluded,
and the patient is instructed to repeat K-K-K-K-K, loudly and sharply, as a one second or less
burst of air is delivered. A characteristic soft palate flutter sound is heard if the procedure is
performed correctly.
If no results are obtained with this technique, the patient is instructed to swallow, and as
the thyroid notch raises up, air pressure is again appUed in the nose. For people who have
trouble with a dry swallow, a sip of water may be given. In the low-pressure chamber, this
method is most often used to get maximum opening of the Eustachian tube. It must be
remembered that with the water technique, prolonged or high pressure might cause damage to
the tympanic membrane vrith even a remote possibility of damage to the round window
membrane and inner ear. As it is important to look at the patient's tympanic membranes before
inflation, it is equally as important to observe them afterwards to determine the extent or
success of the procedure.
A rubber Polifier bag is availsdjle in most drugstores and is useful with the swfilow
technique in children vnth serous otitis media or where a pressure air supply is not available.
The use of Eustachian tube catheterization is not recommended in any case. There have
been cases of air embolism and air in the mediastinum from improper catheterization.
Acute Infectiom. When the tympanic membrane is intact, acute middle ear infectiens are
direct extensions of infections in the nose and nasopharynx, ftequeiitly set up bf improper
blowing of the nose.
Catarrhal otitis media produces blockage of the Eustachian tube and middle ear mucosa
inflammation, without bacterial invasion. The patient usually develops a fullness or plugged
feehng in the ear and may feel as if fluid is present. There is hyperemia of the vascular strip and
8-11
U.S. Naval Fli^t Sui^eon's Manual
aiialus, and occasionally the entire tympanic membrane may be diffusely byperemic. There is
usually httle or no hearing loss or tympanic membrane bulging. Treatment is directed toward
reUeving discomfort through decongestants and analgesics. Antibiotics are usually not indicated.
Acute suppurative otitis media rmilts when virulent bacteria invade the middle ear space,
most frequently as a complication of a cold, influenza, measles, or scarlet fever. MucQpUrulence
is formed in the middle ear space, and all parts of the middle ear may be inflamed from the
Eustachian tube to the mastoid air cells. Deep, sometimes throbbing pain, fever, and a mild to
moderate hearing loss develop. Some people occasionally may have dizziness, nausea, and/or
vomiting.
Initial examination of the ear may ^oi«r tympaiiic membrane hyperemia and slight bulging,
especially in the para flaccida. As the process continues, the bulging and inflammation distort or
obscure the normal landmarks on the tympanic membrane. Finally, an area of blanching
develops that signals imminent perforation. With perforation, the patient's pain is usually
decreased, but drainage may be inadequate.
Treatment should be initiated as soon as possible with adequate doses of antibiotics, moat
often one of the penicillin groups. Medication should be continued for seven to ten days to
assure complete eradication even in the mastoid cells. Antihistamine decongestant or plain
decongestant medication by mouth is prescribed. Control of pain, hydration, and rest are also
very important.
If perforation appears to be imminent, it is wise to do a myringotomy (Figure 8-6) to assure
adequate drainage and clear perforation that heals more rapidly. If the tympanic membrane
ruptures spontaneously, suction cleaning should be done, and if the drainage area is inadequate,
consideration should be given to enlarging it by myringotomy. The draining ear should be
cleaned frequently to prevent chronic complications. Topical medication is only used in large
perforations or when an external otitis is present or develops from the drainage.
Chronic Perforation of the Tympanic Membrane. Small, dry, central perforations may be
closed by cauterizing the edge of the perforation with trichloroacetic acid. It can be left open or
one may elect to place a small patch made from cigarette paper or other thin paper over the
perforation. Uaially the patch is moistened in antibiotic drops before appUcation.
Large perforations with a dry middle ear may be closed by a tissue graft if the Eustachian
tube is functioning. Testing of this function is fairly accurate by tympanography. Poor or absent
Eustachian tube function gives surgery a poor chance for success. If the ossicles show fixation or
8-12
Otorhinolaryngology
Manutirium
Parsflaccida in
notch of Rivinus
Short process of malleus
Anterior malleolar fold
ANTERIOR SUPERIOR
QUADRANT
' Parstensa
Eustachian tube
Cone of light
^ Posterior malleolar fold
POSTERIOR SUPERIOR
\ QUADRANT
Long process
of incus
Stapes
Lenticular process
Umbo
Fibrous anulus
VERTICAL
MYRINGOTOMY SITES
CLASSIC
MYRINGOTOMY SITES
Promontory
Abnormal exposed
jugular butb
Figure 8-6. Middle ear anatomy and myringotomy sites
(A adapted from and B and C from Saunders & Paparella, 1968, published by permiBsion of The C.V . Mosby Co.).
8-13
U.S. Naval Flight Surgeon's Manual
if there is considerable scarring with adhesions, hearing might decrease somewhat further even
though the perforation is closed, as a result of the poorer transmission of sound and the
cancellation effect of sound striking both windows at the same time. A perforation, per se,
which dlows for ^qual^ation of pressure between tiie middle ear atid ike atmosphere does not
affect flying. Sudden cold or hot am or water and loud noise may cause vertigo more easily in
the perforated ear. Of course, water in a perforated ear usually leads to infection and drainage.
In the management of chronic draining eia, one has two objectives: First, attempt to
control or clear the infection, and second, prevent formation of a cholesteatoma or mastoiditis
that might lead t<? further destruction of hearing, labyrinthitis, meningitis, lateral sinus
thrombosis, or brain abscess.
The principles of treatment are meticulous cleaning of the canal perforation and middle ear,
removal of granulation tissue, and control of the infection with both systemic and topical
antibiotics. The Neomycin-Cortisone or Garamycin solutions may be introduced into the middle
ear. One technique is to fill Ihe canal with the solution and gentiy compress the tragus into the
meatus while swallowing. If the otorrhea is not :too heavy, antibiotic powders may be
insufflated, or the older powder preparations, .such as Sulzberger's one percent iodine and
one percent boric acid, are often effective. For thick drainage and debris, it may be necessary to
irrigate with a 1.5 or 2 percent acetic acid solution. The area should be suctioned clean and dry
before using the antibiotic drops or powders to increase their effectiveness.
Hie Inner Ear
Anatomy. Situated medial to the middle car entirely within the petrous portion of the
temporal bone lies the inner ear. It is composed of dense, compact bone two to three
millimeters thick, forming the osseous labyrinth. This is divided into semicircular canals,
vestibule, and cochlea. Within the bony labyrinth is a membranous counterpart. The supporting
fluid outside of the membranous labyrinth is perilymph. It is somewhat similar to cerebrospinal
fluid and is high in sodium content. The fluid inside the membranous labyrinth, endolymph, has
a high potassium content.
The cochlea is a two and a half -turn coil about a central core called the modiolus, with the
apex pointing anteriorly and laterally. There are three compartments. The first two, the scala
vestibuli associated with the oval window and the scala tympani associated with the round
window, contain perilymph and are joined at the apex oflhecochleittfarou^ thehelicotreina.
The third or central compartment is the aciQa media or cochlear duct, containing endolymph. It
contains the neural end organ of hearing, the organ of Corti, which rests on the thick basilar
membrane that separates this compartment from the scala tympani. The delicate Reissner's
8-14
Otorhinolaiyngolo^
membrane separates the scala media from the scala vestibuU. The organ of Corti contains about
24,000 hair cells arranged throu^out the cochlea as a single row of inner cells and from three
to five rows of outer cells. Between them, they form a somewhat triangular tunnel of Corti that
ha& its own eli^tly different fluid, Cortilymph. It is known that high frequency vSptinds
stimulate the hair cells near the vestibule, and low frequency sounds stimulate those near the
apex. The area of the promontory or basilar turn of the cochlea is stimulated by frequencies in
the range of 3000 to 5000 Hz; it appears to be the most vulnerable to acoustic trauma, probably
from the shearing force in the fluid so near the stapes footplate and the beginning curve itt the
SQak.
Trauma. Temporal bone fractures are for the most part of two types. The longitudinal or
middle fossa fracture that parallels the long axis of the petrous pyramid is usually due to forces
applied to the temporoparietal region. The middle ear is alwayai damaged. The tympanic
membrane is torn and bleeds. The IdiyrintMne Ciqisule is usually spared, as is the facial nerve.
Longitudinal temporal bone fractures are four times more frequent than the transverse variety.
The transverse or posterior fossa fractures usually result from forces applied to tiie occipital or
occipitomastoid region. There is essentially a fracture of the labyrinth that spares the middle
ear. There may be hemotympanum, but rarely rupture of the tympanic membrane. Usually,
there is both cochlear and vestibular function loss, and the facial nerve is damaged in the
internal auditory meatus or horizontal portion.
Initial tteatment ^ould include cranud checks, prophylactic antibiotics, and a complete
neurologic evaluation. The patient should be moved to the care of a neurosurgeon/otologist as
soon as condition permits. A base line audiogram is valuable if the patient's condition permits.
Barotrauma. In the past few years, an increasing number of cases of barotrauma to the inner
ear have been reported from the diving community, and several cases of proven rupture of the
round window membrane have been reported or evahiated at fiie Naval Aerospace Medical
Mstitute. These have been associated with ovetiy aggressive use of the Valsalva maneuver to
clear what the patient thou^t was an ear block. In reality, the problem was an over-inflated
middle ear and distended tympanic membrane, which gives a similar blocked feeling, but usually
has no pain. When the round window membrane ruptures, there may be variable degrees of
tinnitus and persistent or positional vertigo, often with nausea and vomiting. Calories are usually
diminished on the involved side, and a sensorineural heariii^ loss, often across the board, is
present with poor discrimination of words.
The key to successful treatment is early suspicion and diagnosis by the Flight Surgeon
and immediate repair by the otologist,' Most complete recoveries have had repairs within
8-15
U.S. Naval Fli^t Surgeon's Manual
48 hours. The Fhght Surgeon is reminded that a quick, simple tuning fork test will
separate nerve loss from a conductive loss.
Sudden Idiopathic Hearing Loss. Apoplectic onset of hearing loss is rare, but it is known to
ctacur. It is usually unilateifal alid often associated with tfaiiSient vertigo and persistent tinnitus.
Tflierapy must be instituted within 48 hours to be most effective.
There have been three likely causes proposed: (1) occlusion of tiie internal auditory artery
by spasm or thrombosis, (2) subclinical mumps, and (3) a single episode of Meniere's resulting in
permanent loss of cochlear function.
A "sho%un" treatment regimen is most effective as foBows:
1. Mandatory bed rest of seven to ten days
2. Donnatal or tincture Belladonna q.i.d.
3. Nicotinic acid flushing q.i.d.
4. Histamine vasodilation using 2.75 mg of histamine in 200 ml of five percent dextrose in
water I.V. at a rate to cause flushing, but not cause headache or significant drop in
blood pressure
5. Dextron, 500 cc per day (not with histamine)
6. Systemic steroids, such as Decadron, with high initial dose, tapering q.o.d. to a
maintenance dose that is continued for one or two weeks.
Hearing threshold and speech testing are done at regular intervals, initially q.o.d., then at
longer intervals in the insuing wfedks and monflis. Most patients have some residual hearing loss.
Aviators must be considered on an individual basis fof return to duty. This is mostiy determined
by the amount of hearing deficit, fee completion of an extensive workup for tumor and
neurological or other disease, and discontinuance of maintenance medication, such as histamine
and nicotinic acid.
Nystagmus
The search for the presence or absence of spontaneous or positional nystagmus is an integral
part of the otoneurological examination and the fitness for duty examination.
Nystagmus is called right or left according to the direction of the rapid eye movement or
quick component. When nystagmus is provoked only in the direction of the quick component,
it is termed "first degree." When nystagmus is also noted in forward gaze, it is "second degree,"
and with nystagmus present in all directions of gaze, it is "third degree." Nystagmus is further
8-16
Otorhinolaryngology
categorized as vertical, oblique (rare), horizontal, or rotatory. Proper evaluation calls for
observation of the eyes in the right, left, upward, downward, and primary positions. If the
patient is asked to look too far on lateral gaze, a few flicks of nystagmus are frequently seen and
are a normal phenomenon of accommodation. After the test for i^on^eous ftyflapJUSj tests
for positional nystagmus are carried out with the patient's eyes in the straight ahead position.
The method most often used is that of Cathorne, Dix, and Hallpike. The patient is rapidly
placed supine with the head hanging over the edge of the table, and the eyes are observed for
60 seconds. The patient is then raised up and then returned to the hyperextended position with
flie head in one direction, again for 60 seconds. The procedure is repeated in the opposite
direction. Nystagmus, if present, should be immediately recorded as to type, direction, aptitude,
and intensity. The position should be held until the nystagmus subsides; however, if it persists
longer than 60 seconds, it is considered permanent. In older persons where vertebral artery
occlusion may be the cause of the nystagmus and vertigo, one must use caution and good
judgement to assure that the patient is not left in this position too long.
Unidirectiontd nystagmus is usually of peripheral origin and occurs in the horizontal plane.
Ttie quick component towaard the uninvolved ear. Caloric response is usually hypoactive or
absent. When caloric tests are normal, unidirectional nystagmus may be of central origin. The
nystagmus is usually the strongest, and often only present, when gaze is directed toward the side
of the quick component (first degree). The diagnostic characteristics of nystagmus are given in
Tables 8-1 and 8-2.
Ji&iltidir©5tional nystf^mus is su^estive of central involvement, i.e. , a lesion anywhere in
the brain. Most often, however, it results from a posterior fossa lesion where the bulk of the
vestibulocerebellar units are located. The quick component is usually permanent and toward the
side of the lesion. True vertigo is less frequent, and ataxia may be evident in central lesions.
Table 8-3 pro^ddes a listing of diagnostic criteria helpful in differentiating between central and
peripheral vertigo.
Drugs often produce characteristic nystagmus. Opium and Demerol produce a vertical
downward nystagmus. Positional nystagmus is found with barbiturates and alcohol. Any patient
who demonstrates a spontaneous positional nystagmus with no other abnormality of
labyrinthine function should be checked for barbiturate ingestion.
A most interesting aoid ^aractertstic positional nysl£^US is «een with alcohol intoxication.
Hie nystagmus is typically in two phases and is often recorded as PAN (positional alcohol
nystagmus) 1 and 11. As little as 0.02 percent blood concentration may produce both phases.
Phase I begins about 30 minutes after ingestion, as the blood alcohol peaks, and lasts
8-17
U.S. Naval Flight Surgeon's Manual
approximately three and a half hours. The nystagmus is always in the direction of the gaze or
toward the position of the head, for example, a right-beating nystagmus appears with right gaze,
head turned t® the right or if the right side of the patient's head is down in tlie lateral position.
There is ,a gradual diminution after the peak and an intermediate period of itbout 1.7 hotitg in
which there is no nystagmus. Approximately five hours after the initial ingestion, PAN n begins,
and the nystagmus is in the opposite direction of the gaze or lateral head position and persists
for several hoUBS after the Wood alcohol level has disappeared. PANII nystagmus is greatest
when the "hangover" symptoms are greatest.
Table 8-1
Spontaneous Vestibular Nystagmus
II.
Peripheral
(Labyrinth, Vestibular Nerve)
Central (GNS)
Form
Horizontal-rotatory
Horizontal; vertical; diagonal;
rotatory; multiple; retractorius;
convergence; pendular; alternating
Frequency
y^-e/sec.
Any frequency, usually low or
variable at long Intervals (weeks
to monthsl
Intensity
Decreasing intensity
Constant
Direction of fast component
Tow/ards "stimulated" labyrinth or
away from "destroyed" labyrinth
Towards side of CNS lesion
Duration
lUinutes to weeks
Weeks to months
Dissoctation between eyes
None
Possible
Vertigo
Present
Present or absent
Cochlear signs
Frequently present
Seldom present
Autonomic nervous system signs
Definite
Less definite or absent
Past pointing and falling
Direction of slow phase
Direction of fast phase
(Toglia, 1967, published by permission of Grune & Stratton, Inc.)
Diseases or Clinical Syndromes of Otolo^c Origin
The majority of cases of dizziness which the Flight Surgeon will see associated with disease
or injury of the inner ear or eighth cranial nerve are acute labyrinthitis, epidemic vertigo,
vestibular neuronitis, Meniere's disease, acoustic neuroma, benign paroxysmal positional vertigo,
and trauma. These must be differentiated from the many causes of dizziness or vertigo
(Tahle84).
8-18
Otorhinolary ngology
Table 8-2
Differences Between Peripheral and Central Positional Nystagmus
Peripheral
Central
Latency
None
Persistence
Disappears within 50 seconds
Lasts longer than one minute
Fatigability
Disappears on repetition
Repeatable
Positions
Present in one position
Present in multiple positions
Vertigo
Always present
Occasionady absent, and only
nystagmus present
Direction of nystagmus
One direction
Changing directions in
different positions
Incidence
85 percent of all cases
10 to 15 percent of all cases
(Spector, 1967, published by permission of Grune & Stratton, Inc.)
Table 8-3
Differentiation of Central from Peripheral Vertigo
Peripheral
(Labyrinth, Vestibuiair Nerve)
Central (CNS)
Hallucination of movement
Definite
Less definite
Onset
Usually paroxysmal
Seldom paroxysmal
lirtensity
Usually severe
Seldom severe
Duration
Minutes to weeks
Weeks to months
Influenced by head position
Frequently
Seldom
Nystagmus
Present
Present or absent
Autonomic nervous system symptoms
Definite
Less definite or absent
Tinnitus
FrectUjently present
Seldom preseht
Deafness
Frei^uently present
Seldom present
Disturbances of consciousness
Seldom present
More frequently present
Other neurological signs
Usually absent
Frequently present
(Togiia, 1967, published by permission of Grune & Stratton, Inc.)
8-19
U.S. Naval Flight Surgeon's Manual
Table 8-4
Causes of Dizziness and/or Vertigo
Otologic
Impacted cerumen
Trauma to the inner ear or eighth cranial
neiT(e foomrnotio labyrlnthi)
Dysfunction of the eustachian tube
Acute otitis media
Labyrinthitis
Labyrinthine fistula
Bilateral nonfunctioning equilibrial labyrinths
Motion stckne®
Meniere's disease
Lermoyez syndrome
Vestibular neuronitis
Vasculitis involving the internal auditory
artery or vestibular emissary veins
Tumors of middle ear and inner ear
Ototoxic drugs
"Focal infection" from tonsils, adenoids,
periapical tooth abscesses, and chronically
infected sinusas
Sinusitis, acute or subacute
Systemic
Allergic reactions involving the inner ear
Dizziness of the aged due to indeterminate
vascular cause or end-organ degeneration
due to aging process
Cardiac diseases
Hypertension (paroxysmal)
Hypotension (syncope)
Hyptflfafctive carotid reflex
Btood dyscrasias (anemia, leukemia, lym-
phomas, reticulosis, polycythemia, purpura)
Cogan's syndrome (nonsyphilitic interstitial
keratitis with vestibulocochl^r symptoms—
panarteritis nodosa)
Episodes of hypoglycemia
Hypocortoadrenal ism
Cervical myalgia
(WiMiams, 1967, published by permission of Grune & Stratton,
Neurologic
Degenerating and demyelinating diseases,
especially multiple sclerosis
Posterior fossa lesions
Fractures, cystic arachnoiditis, syringobul-
bia, platybasia and Arnold-Chiarl
malformations
Neoplasms and subdural hematomas
Supratentorial lesions with displacement
of the brainstem
Migraine-like syndromes
Convulsive disorders (vestibular epilepsy,
vertiginous epilepsy)
Temporal lobe lesions with irritation of
cortical vestibular areas
Tox ic- infectious conditions
Aseptic meningencephalitis
Brain abscess
Common viral diseases such as mumps,
measles, whooping cough
Vascular, including atherosclerosis,
thrombosis, embolic occlusion, and
hemorrhage, especially in vessels to
the brainstem.
Ophthalmologic
Nonconcomitant strabisniis
Refractive errors
Optdcinetic vaitigo
Psychogenic \
Tension-anxiety state
Conversion reactions
Neuroses (agaraphobia, claustrophobia)
Hyperventilation syndrome
8-20
Otoihinolaryngology
Labyrinthitis. Labyrinthitis has many classifications, but, in general, it is serous, diffuse,
destructive, or toxic. Serous and diffuse destructive labyrinthitis are associated with otitis
media, cholesteatoma, or ear surgery. When the disease is of the serous type, the vestibular m&
cochlear functions are depressed, with the vestibular symptoms usually preceding the cochlear
depression by a few hours to several days. There is usually spontaneous nystagmus to the
opposite ear, nausea and vomiting, true vertigo, ataxia, past-pointing, and loss of hearing.
In patients with chronic ear disease, especially cholesteatoma, a fistula test should be
performed by exerting pressure and then suction using a pneumo-otoscope. Production of
nystagmus and vertigo indicates the presence of a labyrinthine fistula. An acute, initially severe,
and sudden onset of symptoms May be a^ociated with the erosion into the laby l iiith; however,
in cholesteotoma, the lining or sac protects the labyrinth, and only quick head movements or
pressure applied in the canals cause vertigo in many cases. Patients who have had ear surgery or
manipulation of the stapes may have all the usual findings, except nystagmus.
In isolated serous labyrinthitis, there is usually return of labyrinthine function over weeks or
months. If any fistula is suspected or injury occurred in surgery, systemic antibiotics are
indicated. With fistulas, there is often a permanent nerve-type hearing loss, and some patients
have chronic positional vertigo.
Suppurative labyrinthitis results in violent and sudden onset of vertigo, disturbed
equilibrium, nystagmus, and vomiting. Cochlear and vestibular responses are lost. Complications
such as metiingitis or brain abscess lead to toxic ^mptoms of headache, malaise, and fever.
Vigorous therapy with antibiotics and surgery must be instituted, and some small mortality can
be expected even with treatment. For those that recover, there is usually no recovery of the
cochlear or vestibular responses, and three to five weeks are required for compensation. Return
to a flying status is not recommended, except in the mildest cases. It is often impossible to be
sure of complete eradication of disease, and there is questionable compensation for loss of
hearing and labyrinthine function and occasional residual ataxia.
Toxic labyrinthitis is one of the most common types seen, and a great deal of disagreement
remains about its classification. The etiology ranges from acute febrile diseases to toxic or
chemical substances to idiopathic. The most common eharaeteristic is whirling vertigo with
^adual onset reachiiig a maximum in 24 to 48 hours, and at its hei^t, there may be nausea and
vomiting. There may be no cochlear or vestibular abnormalities in those cases associated with or
following acute febrile illness, but when associated with drugs, either system may be affected.
Usually there is recovery from vertigo in three to six weeks.
8-21
U.S. Naval Flight Surgeon's Manual
Most commonly, toxic labyrinthitis is associated with pneumonia, cholecystitis, influenza,
allergy, extreme fatigue, overindulgence in food or alcohol, and certain ototoxic drugs
(Table 8-5), Palliative treatmeiit wiHi antivert^inous drugs (Table 8-6) and bed rest is helpful.
The physioiau should always be aware of a missed or changing diagnosis with these patients.
They should not be dismissed with the "they always get well" attitude.
Table 8-5
Ototoxic Drugs
Toxic to Cochlea and/or Labyrtnlfi
Causing the Symptom Dizziness
Chloroqujne
Antihypertensives
Dihydrostrepto myci n
Barbiturates
Ethacrynic acid (Edecrin)
CNS depr«ssants
Furosemide (lasix)
Estrogens
Gentamicin
Phenothiazines
Karamycin
Phenylbutazone
Neomycin
Oral contraceptives
Quiriidfne
Quinine
Salicylates
Streptomycin
Tobramycin
Vancomycin
Chloramphenicoi (topically)
Antibiotic Otu^xicity
Vestibular Toxicity
Dri^
Cochlear Toxicity
(Least)
Neomycin
(Most)
1
Kanamyctn
Gentamicin
t
(IVIost)
Streptomycin
(Least)
Epidemic Vertigo. Although to a great extent this dise^ miy be of central origin, it is
important to differentiate it from other vertiginous conditions, and this can often only be done
by exclusion. Characteristically, symptoms are acute onset of severe dizziness, nausea, vomiting,
a sbght fever, headache, and asthenia, with a duration of several weeks to months. Recovery,
however, is usual. There is usually an epidemic character to the disease, and it is associated with
either an upper respiratory infection or gastroenteritiB. Caloric and audiologic tests usually are
normd, but spinal fluid may diow some lymplMJcytic cells. Cases with gastrointestinal
symptonis are more frequent in mid-January, and those with upper respiratory symptoms occur
in the autumn. Laboratory tests are of little value.
8-22
Otorhinolaryngology
Table 8-6
Antivertiginous Drugs
Generic Name
Trade Name
Hours
of Effect
Adult
Dose (mg)
Availability
Cydizine
Marezine
4
50
Tablets: 50 mg
Parenteral Injection: 50 mg/ml
Suppositories, pediatric:
50 and 1 00 mg
Dextroamphetamine
Dexedrine
8
5-10
Tablets: 5 mg
Spansulsst 5, 1 0, and 1 5 mg
Elixir: S mg/ts)3.
Dimenhydrinate
Dramamine
6
50
Tablets: 50 mg
Liquid: 1^.5 mg/4 ml
Parenteral: 50 mg/ml
Suppositories: 100 mg
Diphenhydramine
Benadryl
6
50
Capsules: 25 and 50 mg
Elixir: 1 2.5 fflQ/S rfil
Parenteral : 10 and 50 mg/ml
Diphenidol
Vontrol
4
25
50
Tablets: 25 mg
Ampules: 2 mM20 mg/ml)
Suppositories: 25 and 50 mg
Meclizine
Antivert
12
50
Tablets: 12.5 and 25 mg;
chewable, 25 mg
Bonine
12
50
Tablets, chewable: 25 mg
Promethazine
Phenergan
12
50
Tablets: 12.5, 25, and 50 mg
Syrup: 6.25 and 25 mg/5 ml
Suppositories: 25 and 50 mg
Scopolamine
Donphen
4
0.2-1
1 or 2 tablets 3 or 4 times/24 hr.,
6jug/tablet with phenobarbital,
1 5 mg., and atropine, 0.02 mg
Treatment is supportive, with variable help from the antivertiginous/antinausea drugs such
as Dramamine, Vontrol, Torecan, and Tigan. These patimts should be aljle to return to flying
within one month after all symptoms have ceased.
Vestibular Neuronitis. Vestibular neuronitis is characterized by an attack of sudden,
debilitating vertigo, nausea, vomiting, and spontaneous nystagmus. In most cases, there appears
to be an antecedent or concomitant infection in the upper respiratory tract, maxillary sinuses,
or teeth. The cochlea is spared, but one or both of the labyrinths have abnormal calofics.
Vestibular symptoms decrease somewhat after a few hours, but they remain fairly severe for the
8-23
U.S. Naval Flight Surgeon s Manual
first week, slowly decreasing over the next four to eight weeks. About 70 percent of these
patients have permanent, decreased caloric function.
Management is directed toward supportive treatment of the ^mptoms and m aggressive
workup to rule out other possible diagnoses. Vestibular neuronitis is a self-limiting disease,
although return to work may require from three to twelve weeks. Generally, an aviator is
permanently grounded for military flying because of the sudden debilitating nature of the
Mtacks which can be recurrent even as long as four years after the initiad attack.
Meniere's Disease. Although much disagreement persists as to wb.ether this is a disease or a
symptom complex, and its etiology is still unknown, there is usually the classical triad of
episodic vertigo, tinnitus, and deafnt^ss. The average age of onset is 44 {Cawthorne & Hewlett,
1954), and it is predominantly unilateral, with only about ten percent of the patients having
bilateral involvement.
The onset of symptoms is insidious, usually with a sensation of dullness or fullness in the
ear, and an initial fluctuation in hearing of 10 to 30 dB, usually in the low tones. The hearing
improves somewhat between attacks, but it continues to deteriorate as time goes on. There may
be increased sensitivity to sound, or music may sound distorted. Tinnitus, varying from a
whistle to a roar, develops, followed by a turning or whirling vertigo that may lead to nausea,
vomiting, and even prostration. Any head movement a^avates the condition, with the vertigo
lasting several hours. Some patients can have fleeting attacks lasting several minutes, and still
others have attacks lasting a week or longer and may take months to regain normal equilibrium.
Besides the fluctuating hearing, spontaneous nystagmus, usually rotary and often direction-
changing, and a direction-fixed, positional nystagmus are the most common findings. The
caloric reaction is usually abnormal. Aside from the hearing loss, Meniere's patients f recpiently
have recruitment and diplacusis, low threshold discomfort, and low discrimination scores. Tone
decay and a Type 11 Bekesy are present. A fairly reliable diagnostic test is the glycerin test,
where a patient ingests 1.5 gm/kg body weight of glycerol mixed with equal parts of normal
saline and a few drops of lemon juice. Audiograms are taken immediately and at one, two, and
three hours after ingestion. A positive test is said to be an improvement in hearing of 15 dB in
any one frequency from 250 to 4000 Hz or 12 percent improvement in the discriminating score.
There is no effective, long-term treatment for Meniere's disease. For many years, some
physicians have controlled their patients with a neutral-ash, salt-free diet, supplemented with
diuretics. Shea (1975) recommends a regimen of bed rest, Valium, low salt, diuretics, and no
smoking, plus inhalation of 5 percent carbon dioxide and 95 percent oxygen for 30 minutes
8-24
Otorhinolaiyngology
q.i.d. and 2.75 mgm of histamine diphosphate in 250 cc of lactated Ringer's solution I. V. b.i.d.
Other drugs, given inttwidually, that are reported to be effective for an aeute attack are
1/150 grain AtrdpmeXV.* Valium 10 mgm LV.» and Innovar, whicli must be administered in
the hospital or by an aliesljiesiologist. Vasodilators, such as nicotinic acid, beta-pyridylcirbinol,
Roniacol, or Arlidin, are usually ineffective in Meniere's, as are the antivertiginous drugs. There
have been several surgical treatments for Meniere's with some success in a certain percentage of
patients. These range from the endolymphatic shunt to destructive labyrinthotomy in the moat
severe, uncontrolled cases. Patients with a diagnosis of Meniere's are permanenl^ g^uaM» M
only the patient with a rare surgical cure has ever been allowed to fly by the Federal Aviation
Agency.
Acoustic Neuroma. An acoustic neuroma is a fairly rare, extremely slow growing neoplasm
that originates on the vestibular portion of the eighth cranial nepe in the internal auditory
canal. It constitutes about eight to tett percent of # brain tumors and is most common in |he
fourth and fifth decade of Ufe. Early diagnosis, which offers the best chance for a surgical cure
and the least morbidity/mortahty, is often based on a strong suspicion. Symptoms, often
difficult to pinpoint but most often present, are steady, unilateral tinnitus, hearing loss, and a
feeling of unsteadiness. Some patients have vague complaints of headache, local retroaural
discomfort, and facial paresthesia or pain. A significant finding is a speech discrimination much
more severe than indicated by a pure-tone heming test.
Dif^ostie evaluation should include a complete audiologic examination of pure tone and
speech, Bekesy, tone decay, stapedial reflex, and small increment sensitivity index (SISI) tests.
Stenver's and Town's X-rays are valuable for an initial screen, but tomograms, computerized
axial tomography scans, or a posterior fossa myelogram are more often necessary. A spinal tap is
indicated, as well as vestibular testing. Typically, there is a sensorineural-type hearing with poor
speech discrimination filSt fe inconsistent witii the ptite-tone test, absence of recruitment or low
SISI scores, pronounced tone decay, a type HI or IV Bekesy tracing, reduced caloric response,
widening of the internal auditory canal, decreased corneal sensitivity on the involved side, and
decreased or absent stapedial refiex.
Suspected cases, which are not diagnostic, should be kept under the watchM eye of m
otolaryngolo^t or neurologist and not dismissed or f orgottfeni aftef te uaiiial w#kup.
Benign Paroxysmal Positional Vertigo. Benign paroxysmal positional vertigo must be
differentiated from Meniere's and eighth nerve tumors. In general, onset of nystagmus and
vertigo occur when the head moves to a certain position. There usually is a latettt period of
several seconds, and the nystagmus fatigues with repeated testitig. Most cases have normal
8-25
U.S. iNaval Flight Surgeon's Manual
calorics and audiologic examinations. Symptoms abate in about eight weeks, but they may recur
or even last for years. There is no treatment except avoidance of the position that creates the
nystagmus and vertigo, as well as rfeassuraiice to tJie patient. Klots should be grounded until all
symptoms have disappeared, and each case must be considered on an individual basis.
Rhinology
Nasal and Sinus Physiology
The primary functions of the nose are filtration, warming, and humidification of air; it also
subserves the sense of smell, and it is the origin and recipient of numerous reflex areas. The
sinuses have no primary function.
Air filtration is accomplished by the vibrissae in the anterior nares and by mucus. Most of
the mucous glands are in the nasal mucosa. The mueous blanket is moved by cilia toward the
nasopharynx at the rate of five mm per minute. Although amazingly resistent to heat, cold,
ftimes, dust, and chemicals, the cilia are most vulnerable to drying from inspired dry air, such as
central heating or 100 percent oxygen.
Air flow during inspiration is directed over the turbinates to the roof of the nasal cavity and
Jlien into the nasopharynx. The air is warmed by heat transfer from the mucous membranes.
During expiration, the air makes a loop before exiting the nose anteriorly, allowing for retention
of liie moisture in the air. The air flow volume is regulated by tiie changing size of the
turbinates.
Bacterial Diseases of the Nose
Vestibulitis. An inflammation of the hair follicles in the nasal vestibule may cause chronic
crusting and tenderness of the nasal tip or ala; it is often recurrent. Treatment consists of gentle
cleaning of the nasal vestibule and the application of topical antibiotic ointment, usually
containing Neomycin, two or three times daily. Ophthalmic ointments work well, but treatment
must be continued for two to three weeks after symptoms disappear to prevent recurrences.
Fumnculosis. Furunculosis of the vestibule is also common and usually associated with
digital trauma and nose blowing. A t:rack in the skin allows the entrance of strep or staph
organisms. Most infections localize, but occasionally they may become a spreading cellulitis.
Squeezing or incising the area is diulgerous, as it may cause spread to the cavernous sinus. Pain
and systemic symptoms may be marked. Treatment consists of a "hands off" policy, adequate
doses of appropriate antibiotics, hot, moist packs, and good analgesics.
8-26
Otorhinolaryngology
Rhinitis. Rhinitis can develop as a complication of an upper respiratory infection if
symptoms last longer than seven to ten days. Thick yellow or greenish nasal drainage, fever,
thraat and ear pain, and productive cough suggest complications. ExC^essive Wowing of the nose,
which forces bacteria into the sinuses and Eustachian tube and traumatizes the sinus orifices,
and severe coughing, which strips the cilia from the bronchial lining, are the most common
causes.
Treatment should place emphasis on maintaining good nasal and sinus drainage, good tissue
hydration, and rest; antibiotics are used fot bacterial infections or complications. The
penicillins, erythromycin, or the tetracyclines, in order of preference, handle most complica-
tions, but cultures should be taken to provide help in resistant cases.
In general, pilots or flight personnel should not fly with a cold. Even a slight amount of
nasal congestion and tissue edema may be enough to interfere with pressure equalization of the
sinuses and ears, leadit^ to aerotitis, aeroanualis, or barometric vertigo. The Flight Surgeon
should stroi^y advise against self-medication and frequently reiterate the many predictable,
immeasurable factors, such as level of awareness and performance, that may be affected by
disease or medication. The FUght Surgeon must make individual judgements, depending on the
aircraft, airman's job, type of flight, and medication, when deciding to ground flight personnel.
Before personnel are allowed to return to flight status, a careful examination of the ears, nose,
and throat should be made. Symptoms are often gone several days bisfore the tissues return to
normal and before essential functions return sufficiently to handle the many different and rapid
environmental changes associated with flying.
Diseases of the Nose and Sinuses
AUergic Rhinitis. Allergic rhinitis, a very unpredictable and difficult problem in aviation,
may be acute or chronic, seasonal or perennial. Common symptoms are nasal obstruction, clear
rhinorrhea, sneezing, itching of the eyes, soft palate, and nose, and occasional associated
headache, mostly frontal. Some cases of allergic rhinitis are similar to a cold, but they usually
last only one or two days or over 10 days and are more frequent than viral upper respiratory
infections.
Seasonal allergies are often caused by pollens from grasses, trees, or flowers and last two or
three weeks. If a specific allergen is found, desensitization is often effective. After an allergy
shot, a pilot is grounded for at least six hours. Perennial rhinitis can be quite variable with no
pattern, or it may be nearly constaiit. AUei^es may be caused by house dust, molds, dog
dander, wool, feathers, tobacco pollutants, or food. Avoidance, if possible, is the best method
of control; however, desensitization may be effective for dusts and molds.
8-27
U.S. Naval Fli^t Surgeon's Manual
Examination of the nasal mucosa often reveals edema and paUor of the turbinates, especially
liie inferior turbinates and the anterior tips of the middle turbinates. The turbinates may be s*
ei:^oi^ged. they appear purple. The posterior turbinate tips may protrude into flie nasopharynx
or becQWofi irregular and look like mulberries. Red or inflamed mucosa has also been noted,
especially if the allergen is a pollutant
A basic allergy workup should include the following:
1. History — present, childhood, family
2. Nasal smear for eosinophiles
3. Sinus X-rays
4. Complete blood count
5. Thyroid function test
6. Total protein and gamma globulin blood levels.
The basic treatment measures are as follows:
1. Take antihistamines, with or without decongestants. Alternating the ailtihistaniifie every
two weeks is often effective.
2. Cover pillows and mattress with plastic.
3. Cover overstuffed fiimiture,
. 4. Eliminate wool from bedding.
5. Remove domestic animals from the house.
6. Air-condition the house. 1
7. Avoid milk and e^ products; other foods can be eliminated, one at a time, a week apart.
8. Use nonallergic cosmetics.
Severe allergy attacks may require a short course of systemic steroids for control. Milder
cases that create obstruction of the nasal airway and sinus orifices can often be helped by
topical steroids in an aerosol form, such as Decadron or Beclamethazone.
Nonallergic Rhinitis. Nonallergic rhinitis, often included under tfie term of vasomotor
rhinitis, has as the most common symptoms chronic, intermittent, often alternating nasal
stuffiness or obstruction, and postnasal drip. In the course of treatment, it is important to rule
lAir conditioners may contain much dust and mold, causing more trouble for a person with allergies to these
substances. Electrostatic filters may do a better job, but may produce ozone which is toxic. If the first outlet is
eight to ten feet from the unit, it is ufiuaUy safe. Huraidifieation is good for the dry nasal nracosa, but it also
increases the growth of molds in the house.
8-28
Otorhinolaryngology
out allergies, to explain the physiology of the nose to the patient, and to prevent the overuse of
nose drops or inhalers that may cause a rhinitis medicamentosa. Once rhinitis medicamentosa
develops, it can only be cured by complete abstinence from nose drops. In about three weeks,
the nonnal reflex activity sJiould retjim. Septal deviations &ottld he corrected if th«ey we a
factor in obstructions. Humidification of the house or bedroom, or the use of Proetz solution or
ouitaients to prevent drying of the mucosa is often helpful. Thyroid function may be a factor in
some cases; for borderline hypothyroid states, thyroid extract or Cytomel has been effective.
Certain emotional states cause nasal symptoms, and they often respond when this problem has
been explored or treated. Rhinitis of pregnancy usually responds to no treatment except
deKvery. Certson antihypertensive and birth control pUls may cause nasal congestion; decrcMe or
change in the drugs often improves or cures the problem.
Polyps and Polypoid Degeneration. When the nasal mucosa, and in some cases the sinus
mucosa, reacts to allergies or inflammation, edema develops due to increased capillary
permeabUity and transudation of fluid into the cell and extracellular spaces. The mucosa
appears "waterlogged" or "intumescent." Over a period of time, with l^e help of gravity, this
tissue may elongate to form nasal polyps, especially in the region of the middle meatus and
me^illary sinus ostia. In some cases, the anterior tip of the middle turbinate may just remain
edematous, and this condition is called pctlypoid degeneration, rather than a polyp. The tissue
may lose some of m ciha and is replaced with goblet cells.
Polyps and polypoid degeneration may obstruct the sinus ostia leading to acute and durphie
sinus disease or sinus blocks and, therefore, should be removed when obstructive. Small, or
single, nonobstructive polyps need not be removed unless they enlarge. Occasionally, polyps are
found within the maxillary sinus; these polyps eventually move out of the sinus ostium and into
the nasopharynx, where they expand in size. These polpys are called antrochoanal or choanal
polyps, and their removal requires a Caldwell- Luc antrostomy to remove the base and prevent
recurrence. Polyps in the maxillary sinuses are disquaUfying for aviation candidates, as is na^al
polyposis. A possfltle exception can be made for a single, small polyp on one side in an
asymptomatic, nonaUergic candidate. Recurrence of polyps after removal is common; this is
especially true when the disease remains in the ethmoid sinuses. In some cases, the use of short
courses of tetracycline and topical steroids, such as aerosol Decadron or Beclamethazone, may
reduce the size of the polyps. A common dose schedule is two sprays in each nostril, twice daily
for one week, then one spray in each ntKstril twice daily for four days, finishing with one spray
daily in each nostril for the remainder of the week or longer, if desired. The use of topical
steroids may be irritating to the mucosa, and use beyond one month is not recommended.
8-29
U.S. Naval Fli^t Surgeon^ Manual
Epistaxie
The majority of nosebleeds are caused by trauma and occur from the vascular plexus on the'
anterior septum, known as Kisselbach's plexus or Little's area. Common causes are air drying,
violent sneezing or blowing the nose, and picking the nose. Severe bleeding, especially high
anterior and posterior bleeding, occurs from the ethmoid artery, a branch of the mternid
caMtid, and the sphenopalatine artery, a branch of the external carotid artery.
In general, treatment of simple anterior bleeding should first be direct pressure, for at least
five or ten minutes, against the anterior septum. Pledgets of cotton moistened in a
vasoconstrictor, such as one percent Neo-Synephrine, one percent epinephrine, or one to four
percent cocaine, along witJi pressure, are even more effective; large dots should be gently
suctioned away. If bleeding is controlled, the bleeding site may be cauterized with 25 to
5®'percent trichloroacetic acid, five percent chromic acid, or silver nitrate in a 50 percent
solution or on a stick apphcator. These solutions should be appUed with a small, moist
apphcator under direct vision. Anterior bleeding sites not controlled by direct pressure or
chemical cautery should be infiltrated with Xylocaine and epinephrine, using both the tissue
wheal and the eplr^hrine effect for control. The site may then be cauterized by chemical or
electroeautery ; deep bums or cauterisation of adjacent structuies, such as the ala or vestibule,
must be avoided. If the coagulated fiuid and blood stick to the tip of the cautery and are pulled
off with the coagulum, the bleeding may restart. In those cases where bleeding cannot be
controlled, one might attempt cautery with a suction tip electrode; if this fails, the nose can be
packed with Vaseline and antibiotic ointment impregnated in half -inch selvage gauze. It is best
to pick both sides to prevent loss of the pack by j^ifting of the septd cartilage from a one-sided
pti^isure. Hie pack ^ould be left in place for at least 24 hours, but usually never more than
72 hours. AH raw or cauterized surfaces should be lightly covered with an antibiotic ointment,
and a small piece of compressed Gelfoam over the anterior septum further protects against air
trauma. The ointment application should be repeated three or four times a day.
Posterior bleeding, usually in the older age group, is a serious condition, and, if coupled with
hypertenmon, it requn-es aggressive medical and rhinologtc management The patient should be
admitted to sickbay, sedated, and kept in a head-elevated position. After vasoconstrictor and
topical anesthestic application to both nasal passages, an attempt can be made to control the
posterior bleeding by the use of a specifically designed postnasal balloon, or a common,
15 ccsize Witley catheter. The bidloon is checked before insertion, then it is passed along the
floor of the nose, and when it is in the lower nasopharynx, the baUoon is filled with about 5 cc
of water. It is then drawn back up against the posterior choana and further filled to the point of
tolerable discomfort to the patient. Anterior packing is inserted bilaterally with fixation of the
catheter to the lip or against the packing, but never against the ala or septum to prevent pressure
8-30
Otorhinolaiyngology
necrosis. The posterior pharynx is checked hourly for bleeding, and the hemoglobin and
hematocrit are monitored according to the amount of oozing or bleeding; blood typing and
cross matching are advisable. Blood coagulation studies are usually done, but it is unusual to see
only nasal bleeding witii abnormstlity of Ife clotting ndiecharasfli. A patient with a poeteM&r
nasal pack or balloon is never sent home. He should be closely monitored because of iJie
possibility of a nasovapil f6&M' action when the nasopharynx is packed, that might lead to
apnea and/or hypoxia. Uncontrolled bleeding of the ethmoidal arteries requires ligation in the
orbit or, as a last resort, an internal carotid ligation. Uncontrolled sphenopalatine artery
bleeding requires ligation through a transmaxillary sinus approach, or ligation of the external
carotid in the neck,
A sample epistaxis treatment tray is pictured in Figure 8-7.
Figqne $-7, An ep^taKis treatment tray.
Barotrauma to Sinuses , . . ^
Aerosinusitis results when equalization of pressure between l3^„|Snus cavities and the
atmosphere is prevented by obstruction of their orifices. There are numerous causes, but
heading the Ust is the common cold and allergies. Other causes are anatomic defects, infection,
and polyps. > ■
As an aviator goes to altitude, the outside |>tpwire deerepe?, aiid Comfort may be felt m
the obstructed sinus. It is usually not severe, however, and most often air forces its way out pai?t
8-31
U.S. Naval Fli^t Sturgeon's Manual
the obstruction. When the aviator descends, the pressure in the obstructed sinus remains less
than the surrounding pressure, creating a vacuum effect on the delicate, thin, mucosal lining and
resulting in pain that is often severe. Some fluid may be drawn into the cavity, but the more
serious compHcation is pulling away of the inucoperiostemn, with formation of a hematoma.
Sinus blocks occur most often in the frontal sinus (70 percent), and the aviator must be
poiUfded until the hematoma resohes, and the ostium is patent. This may require three weeks
to three months. For this reason, anyone suspected of a sinus block should have sinus X-rays to
determine the extent of injury and then should be followed at approximately three-week
intervals, until clear.
Treatment of the acute block is as follows:
1. Stop descent in aircraft or low-pressure chamber, if possible, and return to altitude for
pain relief.
2. If available, spray the nasal passage with a vasoconstrictor nasal spray.
3. Do the Valsalva maneuver or use the PoUtzer method.
4. Make a slow depcent equalizing pressure with the above maneuvers.
5. Place patient on antihistamine-decongestant or decongestant therapy.
6. Take screening Water and Caldwell sinus X-rays.
7. If an upper respiratory infection is present, treat wilji antibiotics.
8. Control severe pain ^th-CpdiiR*? or Percodan.
9. If a frontal sinus hematoma is present, ground the aviator for at least three weeks. With
no iq)parent x-ray pathology, the aviator ^ould be grounded for at least 72 hours, or
until any nasal symptoms have been cleared. Recurrent Ixauma may result in mucocele
formation, te^iring a nnigor surgical procedure and permanent grounding.
I
SinusitiB
The majority of acute sinusitis cases follows an acute upper respiratory infection, like the
common cold, and they are often the result of improper nose blowing. Another cause, which
may have a more rapid onset, is swimming or diving; occasionally, an upper molar tooth abcess
breaks into the maxillary antrum. Hie extent and persistence of the infection depends on two
mi^or physiolc^cid principles, ventilation and deainage; tiie treatment is ifirected toward these
principles. Hie most common bacterial causes are the Gram-podlive cocci.
Acute suppurative sinusitis usually has symptoms of nasal congestion and pressure or pain
over the involved sinus. Toxicity is usually mfld, except in esmm of pananusitis when the
frontals or sphenoids are involved. Pus draining from the middle meatus or above the middle
turbinate, pain and pressure over a maxillary or frontal sinus, and decreased transillumination
832
. Otorhinolaryngologjr
may be sufficient to make a diagnosis. The x-ray is indispensable, however, in determining the
extent of the disease, fluid levels, and response to medication, ail of which may direct the
proper approach to treatment.
Maxillary sinusitis, because of its isolated position, may have the least toxicity, but a
persistent fluid level or pain after 48 hours of adequate antibiotic therapy suggests the need for
irrigation of the antrum, either through the natural ostium or through the thin, bony wall of the
inferior meatus. The maxillary sinus mucosa has great reparative power; after removal of the pus
by irrigation, it may clear within a few days. If the antral infection is dental in origin, it is
useless to attempt a cure without treatment of the offending tooth.
Ethmoid sinusitis is probably the most common infection. Due to the proximity of the
ethmoid sinuses to the frontal and maxillary sinuses, ethmoid sinusitis either causes or is
associated with the infections in those sinuses also. Ethmoid infections usually cause more
inflammation and mucos^ swelling. Pain inay be near the root of the nose or frontal region.
Edema of the lower lid is often present Orbit involvement may result in painful eye movement
due to a periostitis about the pulley of the superior oblique muscle or, in the case of rupture
into the orbit, proptosis.
Frontal sinusitis usually is associated with toxicity, frontal headache, often in mid-morning
to late afternoon, tenderness to percussion over the sinus, or pressure on the floor in the
supraorbital region; swelling of the upper eydid may be highly suggestive. Treatment' diould be
vigorous to prevent osteomyelitis of the skull or fistulas that lead to complications, such as soft
tissue or sinus cavity abscesses, meningitis, brain aibscess, and even death.
Sphenoid sinusitis is uncommon, but it may result as a direct extension of infection in
neighboring sinuses, nasal mucosa, or the nasopharynx. The symptoms are variable, but they
may consist of a deep, boring, occipital or parietal headache with inability to concentrate, fever,
malaise, and anorexia. Rupture or osteomyelitis from sphenoid infection leads to rapidly fatal
meningitis or cavernous sinus thrombosis. Diagnosis can usually only be made by suspicion and
x-rays, using proper contrast in the lateral and submental vertex positions; fluid levels will only
be seen if the x-rays are taken in the upright position. These patients require high doses of
intravenous antibiotics and emergency surgicd int^entioh.
Since the cardinal principle of treatment in anus infections is ventihtlion sind drmnoge, the
follovraig treatment is sa^ested:
1. The nasal mucosa must be protected from drying. The patient must be kept hydrated,
and, in some cases, use of a humidifier or vaporizer may help.
8-33
U.S, Naval Fli^t Surgeon's Manual
2. An oral decongestant may be used alone or with an antihistamine. Antihistamines may
make secretions too thick or the mucosa too dry, so it is often helpful to use a
mucous-thinning medication, such as glycerial glyacolate.
3. AntdObiotics are given orally in adequate doses for at least seven, days in most
uncomplicated cases, hut in parasinusitis or cases of moderate to severe toxicity, and
especially in frontal or sphenoid involvement, intravenous antibiotics are necessary.
Most organisms are sensitive to peniciUin or erythromycin, but if is strongly
recommended that a culture be taken from the turbinates and the meatuses. Be sure not
to touch tiie nasal vestibule and hairs, as these areas may have different predominant
organisms. The nasopharynx is another area to obtain a culture from prevalent sinus
drainage.
4. Bed rest, hydration, and ade^ate pam medication are important in patients with
toxicity.
5. Antral irrigation, either through the natural ostium or the inferior meatus puncture
approach, is indicated for persistent pain and/or fluid levels after 48 hours of antibiotic
therapy. Persistent swelling and pain in the frontal sinus region, in spite of intense
therapy, may signal the need for a frontal sinus drainage, usually done by trephine
through the sinus floor. A rubber or plastic tube drain is sutured in place to allow
irrigation and drainage until the natural ostium drainage is reestablished.
6. Daily mucosal shrinkage and gentle nasal suction cleaning may help promote drainage.
7. Local heat is often helpful, not only as comfort to the patient, but to increase the
vitality of the mucosa.
8. Persistent or subacute ethmoid disease may respond to Proetz displacement irrigation.
9. Acute sphenoid infection with toxic signs is an eme^ncy and hfe-threatening situation
requiring imtnediate hospitalization and gui^ry, so dile should always be alert to this
disease, by itself or as a complication ftom tite a&iei ^uses.
Neglected sinus infections or subacute disease lead to chronic irreversible changes in the
sinus mucosa. With chronic purulent drainage or sinus blockage, one usually has to resort to
surgery after conservative treatment fails. For the maxillary sinus, a CaldweU-Luc antrostomy
and/or an intranasal antrostomy (antral window) is most often used. Removal of the ethmoid
cells is most difficult and is done with an intranasal approach when polyps and persistent disease
are present. Chronic sphenoid disease is not only rare, but most difficult to diagnose, because
8-34
Otoriiindlaiyjigology
x-rays may be inconclusive and symptoms extremely variable. Chronic disease in the frontal
sinus, be it osteomyelitis or mucocele formation, dictates a major surgical procedure through
either a bicoronal incision flap approach or the osteoplastic eyebrow incision approach, with
complete removal of the sinus mucosa and obliteration of the sinus, usually with fat. These
surgical procedulfea ahd tteaWeal may never result in relef of nasal symptoms or remove the
tendency toward recurrent infeciion. A frontal swws obliteration is usually disc[ualxfying for
most types of aviation.
Antral cysts, which are frequently seen on the Waters X-ray as a smooth, rounded density in
the lower aspect of the maxillary sinus, are benign, fiQed only with clear or xanthochromic
fluid. They usually require no treatment, unless they fill the sinus, obstruct drainage, and lead
to local symptoitis of cHseiise.
Maxillary Sinus feeiglitioit - XfiieiSi^ Meatos Pmicilxuf;
Anmthesia,
1. Spray mucosa initially with a vasoconstrictor.
2. For local anesthesia use fou- or five percent topical cocaine and two percent Xylocaine
with Epinephrine 1:1000 (dental carpule or equivalent).
3. Apply pledgets of cotton moistened with cocaine {never sloppy wet) itt flie inf^irior
meatus and on the inferior turbinate. After initial ^plication, cocaine an a wire
apphcator is placed against the lateral wall of the mferior meatus about one inch or
1.5 to 2.5 cm behind the anterior edge of the meatus for five minutes.
4. Insert a long (354 inch) needle into flie mferior nieatus until it strikes bone in the area of
the intended puncture and infiltrate with local anesthetic.
Equipment (Figure 8-8).
1. Straight V/i in., 18 gauge spinal needle or equivalent trocar with stylet
2. Sterile saline to which a small amount of Neo-Synephrine may be added
3. One 30 to 50 cc syrit^ and one 5 ec syringe
4. Hastic or rubber extension tabing
5. Culture tube
8-35
U.S. Naval Flight Suigeon's Manual
Figure 8-8. A sinus irrigation tray.
Technique.
1. With the patient in an upright position and tiie head against a firm headrest, the
puncture needle or trocar is inserted into the inferior meatus about two centimeters
posterior to the edge of the inferior meatus and engaged in the thin bone of the lateral
wall of this area.
2. The thumb is placed against the stylet and the needle is directed laterally in line with the
outer canthus of the eye, using the fingers of the opposite hand to steady the needle
(Figure 8-9). Pressure is slowly, but steadily, increased until the needle is felt to
penetrate into the sinus.
3. The needle is pushed into the sinus until it strikes the lateral sinus wall and then
withdrawn about one centimeter. If a low-lying cyst is present, the needle is directed as
far inferior as possible just after penetration to puncture the cyst.
4. Direct observation of the drainage or aspiration with a small syringe may be diagnostic
or produce a pure specimen for culture.
5. The large syringe and extension tubing filled with normal saline are inserted into the
needle and aspiration is attempted. Air bubble or exudate indicates the needle is in the
proper position. No aspiration may mean the needle is in the mucosa, plugged, or not in
the sinus proper.
8-36
Ototl^dliiTyngologjr
Figure B-9. Maxillaiy rinus irrigatian technique.
6. Irrigation is carried out with the patient leaning forward over a large basin with his
mouth open, and gentle, but steady, pressure is applied to the syringe.
7. Instant, severe pain suggests the tteedte is in the miteosa; i^adjust nwSh'B position
and repeat. Intolerance to irrigation pressure dictates termination of the procedure and
possible attempt at natural ostia irrigation. A slow buildup of pressure and occasionally
pain is expected with an obstructed ostia, but it is usually tolerable or relieved as the
sinus is irrigated.
8. Irrigation should be carried out until the washing is clear or, in the case of a clear
irrigation, until at least three full syringes have been used.
9. The final irrigation should be made with tiie sinus ostia dependent. If air can be
aspired, then a syringe fuU of an- may be used to force out the last of the remaining
fluid.
8-37
U.S. Naval Bight Swgeon's Manual
10. The needle is withdrawn with a smooth rapid movement and the nasal passage
immediately inspected for retained pus or thick mucus. This material is aspired, being
sure to include a^iraliOti of lihe posterior floor and middle meatus.
Maxillary Sinus Irrigation — Natural Sinus Ostia
Anesthesia. ^ -
1. Use four or five percent cocaine ^i loGal anesthesia.
2. Vasoconstrict the mucosa.
3. Apply cocaine-moistened pledgets in and around the middle meatus. A long appKcator
containing cocaine may also be inserted posteriorly against the area of the
sphenopalatine nerve exit.
Equipment. A m^illary sinus cannula plus the equipment used for the puncture technique
are required.
Technique.
1. A maxillary sinus cannula is inserted posteriorly into the middle meatus and slowly
brought forward with the tip probing for the oStia in the &tus semilunaris. When the
cannula passes into Ihe ostia,^ it should be anchored with tape to the nose or held in
place by the physician.
2. Aspiration and irrigation are carried out in the same manner as for the needle
irrigation.
Ethmoid Sinus Irrigation
The Proetz displacement technique can be used for irrigation of the frontal, sphenoid, and
maxillary sinus as well as for the ethmoid sinus in non-acute disease.
Equipment.
1. A controlled vacuum source
2. Sterile 100 cc solution container
3. Proetz vacuum apparatus (curved oUve tip glass collection bottle)
4. Sterile bulb or other syringe, 20 cc or laiger
5. Sl«il6 normal saline into which may be added Neo-Synephrine, not to exceed a total
of 1/8 percent.
Otorhinolaryngology
Technique. (Figure 8- 10).
1. Place the patient supine, with head lowered over the edge of the table.
2. Instruct the patient to breathe ordy through the mouth and not to swallow or talk until
instructed.
3. Fill the nose and nasopharynx with the solution through one nostril.
4. Insert the soft rubber or steel olive tip of the vacuum apparatus into one nostril, with no
more than 180 mm Hg of vacuum.
5. iClose the opposite npitlil and have the patient say K-K-K-K-K-K-K-K.
6. Repeat the proeedure several times in each side, or until purulent material is no longer
present.
7. Stop immediately if the patient has severe pain, or if blood* is noted in the irrigation
fluid.
8. Give the patieftt a rest mi allow him to sit up to drain out tiie nose several times durhag
the procedure.
Figure 8-10. Proetz displacement tedinique.
8-39
U.S. Naval Hi^ Surgeon's Manual
Nasal Fractures
Nasal fractures are common injuries which can usually be handled in the clinic or sickbay
by the Flight Surgeon. There are basically three types: (1) a simple depression of the nasal
bones, most often just the tip, (2) lateral displacement of the nasal bones to one side, often as a
green stick fracture ©a one side and impaction on the other, and (3) marked flattening of the
nasal bridge with c&mnnnution of the bones and associated accordion fracture diq>lacement of
the septum.
Shortly after injury, when the airway is compromised, or before profuse swelhng has
occurred, reduction should be accomplished under local or generd anestfiesia. When the injury
is very recent and the patient is still in a shock or "numb"-like state, lateral displaced fractures
em often be reduced without anesthesia by simple, quick, firm, thumb pressure on the convex
aide of flle nose. When soft tissue swelling is marked, distorting the true alignment of the nasal
bones, one may elect to wait four or five days for the swelling to recede before reduction. A
compound fracture should be reduced within a few hours and then have a plastic-type laceration
closure since reduction maneuvers usually tear out delicate sutures. Antibiotic* coverage is
recommended to prevent complications.
Anesthesia TeehnkfUe for Reduction of Nasal Fractures.
1. Shrink the nasal mucosa with one percent Neo-Syneplwine.
2. Use fresh cocaine from one to five percent, most common is four percent.
3. Moisten long, thin, cotton pledgets with cocaine, squeeze out the excess, and Ttment
them into the superior and middle aspects of the nasal passages. They should touch the
septum and turbinate mucosa beneath the nasal bones where reduction instruments are
inserted. The sphenopalatine and long nasopalatine nerves may be blocked by applying
cocaine on a long applicator to the area of the sphenoid rostrum. The area can be
reached by inserting the applicator back past the postmor tip of the middle turbinate.
The ethmoid nerves may be blocked by ^plyang cocaine on an applicator inserted
aiperiorly just exterior to the middle tBSfbinate tif .
4. Local anesthesia, using two percent Xylocaine with epinephrine (dental ^fringe
carpule), is obtained by inserting a long dental needle into the nasal vestibule just
above the upper lateral cartilage at the limen nasi. The needle is slid in the
subcutaneous tissue external to the nasal bones to the desired locations.
5. Infiltration sites are the glabella for the superior trochlear nerve, the inner canthus
region for the ethmoid and the infratrochlear nerves, and, with a more lateral
reinsertion of the needle, the infraorbital notch for the infraorbital nerve. FoHowing an
840
Otorhinolaryngotogy
initial wheal, the needle is slowly withdrawn while injecting a tract of anesthesia from
each side, bilaterally.
6. Local anesthesia of the septum is obtained by injection of the septum just beneath the
tip of the nasal bones and obtaining a "run" of the anesthesia beneath the
mucoperichondrium.
Equipment for Nasal Fracture Reduction (Figure 8-11).
1. Elevator - Most often used is the Sayer elevator. Others are flat scalpel handles or the
Salinger reduction instrument.
2. Bayonet forceps
3. Gelfoam pledgets t
4. Half -inch Vaseline-impregnated selvage gauze, lainiinUni of two tubes
5. Antibiotic ointment
6. Rubber finger cot
7. Quarter-inch regular or plastic tape
8. Malleable metal nasal sphnt.
tiguie 8-11. A nasal reduction tray.
8-41
U.S. Naval M^t Surgeon's Manual
Nasal Fracture Reduction Techniques.
1. Septal Fractures Only
a. Grasp the septum between two fingers, puU forward, up, and side to side, using a
thumb or finger of the opposite hand to unbuckle a concavity.
b. The nose is then packed on both sides to maintain a good alignment alone or
against a stint.
c. Stints of dental wax or Teflon sheets can be used and held in position with
through and through septal sutures.
2. Depressed Nasal Tip
a. Place a finger cot over'the elevator and insert it in either nostril to just beneath the
fracture. Using the fingers of the opposite hand to move and guide the fragment,
hft the fragment with the elevator and slowly withdraw.
b. Place compressed Gelfoam beneath the fracture site on both sides. Selvage gauze
anterior packing, external taping, and a metal splint offer the best results.
3. Lateral Displaced or Comminuted Fracture
a. Measure the distance externally from the nostril to the glabella on the elevator.
Insert the elevator the measured length into the most open side of the nose.
b. With a gteaidy lift of flie elevator, move the fradtuwe further to the deviated side.
Then move the nasal bones across the midline an equal distance to the opposite
side; return the fragments to the midline. Some bleeding is expected, but in the
majority of cases, Gelfoam is all that is required for control, and it helps prevent
adhesions that may occur euperlorly. External tepaig and mistd protection aid in
maiiitjilning al%tmient.
Taping and Splinting Techniques.
1. Apply benzoin solution to the forehead, nose, and cheek areas.
2. If the nose is packed, the initial tape should run from one side to the other parallel
with the dorsum across the packed narcs. Do not pull tight, and allow for tissue
swelling by cutting or pinching the tape at the tip.
3. Fixation of the nose is provided by an initial tape across the dorsum from cheek to
cheek, then a crisscross taping from the forehead to the cheek on both sides. This may
be weaved. in with the dorsal tapes. If the nose is packed, be sure all of the tip is
covered with tape to prevent swelling.
8-42
Otorhinolatyngology
4. A malleable aluminum splint is placed over the nasal taping and held in place by similar
crisscross taping.
5. For drainage, a folded two by two-inch pad taped across the lower lip allows the
patient to breathe and eat witkbuflfgit(^«eifee.
M l^lii^^ Wl^l^^ to Tli^&em md Saunders (1973,
pp. ^7'2M)i*ffis following common erroirs are assodated with treatment of nasal fractures:
1. The doctor attemplB to set a nose that was also fractiired years pr#yjofii4f , but the
patient becomes aware of the old deformity oa^ p&w trauma calls attentioii
to it. .^.i
2. X-rays wmml tt6 ftaetaie w^hm jai((0 is pixt^t, td|@il^ th® doetor's t^c^ ^dgement.
In reaKty, x-rays are of little practical value in management of nasal fractures.
However, they are of great value in mmagemeiit of fractures of the zygoma and
infraorbital sinus. '
3. The doctor regards easy to reduce fractures too seriously, and severe fractures too
lightly, leading to urmecessary anesthesia or poor reduction because of limited
anesthesia.
4. The doctor waits longer than five or six days to reduce the fracture; thereafter,
reduction may be difficult. '
Maxillary Fractures
Maxillary fractures should always be suspected in direct trauma to the face when there is
malocclusion or restriction of mandibular movement, flattening of the ade of the face, a "black
eye" which mcbided ecchymosis and subconjunctival hemorrhage, anesthesia over ^© face
supplied by the infraorbi^Jd nerve, or the more serious sign of diplopia. X-rays are extremely
important in diagnosis, as well as postreduction evalu)rt3iQ|i, J^, i|ill series should include the
Waters, Caldwell, lateral, and submental vertex.
Zygomatic arch fractures can be elevated under local anesthesia through a temporalis fascia
approach or a buccal mucosa approach. All other fssmtam require mm^ e»;tensive open
reduction, often with wire fixation or prophetic support and protection re(piirii^ |he assjfftaRqe
and training of an oral #i^lf^Q%^^^^|MgoiDjp|, or in tiie ease of a true "blow out" fracture, ^
ophthalmologist. -, 1 1
843
U.S. Naval Pli^t Surgeon's Manual
Examination of the Mouth and Pharynx
This part of the ENT examination should be thorough and easy on the patient, but it is
often most difficult and stressing, both for the phyacian and the patient. The following points
and techniques are recommended. The piij^^t shoiydd^li^s be as conxfotiable asS* possible in an
upright position. Explanation and instructions to the patient before the procedure is started are
absolutely necessary. The phfsiqj^ should -rea^re the patient and refrain from using
uncomfortable words, such as gag, putting the mirror down the throat, or puUing the tongue.
The patient should be encouraged to relax his tongue during the oral and pharyngeal
examination and to breathe through his mouth into the head mirror. If there is concern about
disease tranamissiort, the physician can wear a mask. The correct technitple for using a tongue
depressor is to insert the blade into the mouth without touching the tongue and then to press
straight down on the anterior two -thirds of the tongue. Except for hypopharyn^iPOpy, tiie
patient should not stick out his tongue because this raises and firms up the tongue, preventing
good exposure of the tonsils and pharyngeal area. When warming a mirror over a flame, the
physician ^ould always test the back side of the mirror for proper warmth against his wrist or
face so that the patient will not fear being burned. On introduction of ike nasopharyngeal
mirror, sizes #0, 1, or 2, it is helpful to sBde tfie handle along c@tlier of tiie mouth and
touch the patient's face with the finger to steady the minfor. This also helps distract the
patient's thoughts about gagging. The nasopharyngeal mirror may be slipped into the
nasopharynx alongside of the uvula and may even touch the tip, but touching the base of the
tongue ^duld be avoided. When holding the tongue for the laryngeal examination, the under
surface should be wrapped with cotton gauze to protect it from tiie sharp edges of the teeth.
The fingers can be steadied against the lower teefli and upper lip. If the patient sits up straight
and brings his head and chin forward, the larynx is more easily and fuUy visualized. Fingers
against the patient's face steady the mirror (#3, 4, or 5) as it is introduced into the mouth,
without touching the tongue, toward the uvula and soft palate. Often, the cords can be seen
without tbuchii^ tiie soft palate, but if necessary, contact should be positive and firm, with
or no movement after contact is made. If a patient is unable to hreatHe throu^ his mcSilh
vAm requested, it may he necessary to have lima hold his nose closed. These examinatiom
^otdd last only 10 to 15 seconds because of salivation, anxiety, and discomfort. For patients
with hyperactive gag reflexes, mild mucosal anesthetics such as Chloraseptic or Benadryl Elixir
can be tried first. Stronger anesthetic agents such as Cetacaine, one percent Tetracaine, four
percent Xylocaine, or five percent cocaine may be necessary, but all are toxic and rapidly
absorbed from the oral mucosa, so care must be e^el^d in the aniiotin^ and rapidity with
which they are applied. For extremely difficult cases, LY. diazepam (Yiii£^lAit) of 2.S tO 5 mjgm
over a 90 second period of administration, ^es an excellent effect for 15 to 20 minutes. Since
apnea, caine reactions, or cardiac arrest are always a definite danger with these drugs,
resuscitative equipment should be at hand.
844
Otorhinolaiyngology
Common Oral Diseases
Thrush. Since the advent of antibiotics, thrush, formerly seen chiefly in children, is now
being seen in adults when the normal flora is altered. The usually white mucosal lesions are
scraped for microscopic diagnosis of the characteristic yeast cells.
Treatment of choice is usually wilih Mycostatiii suspension, 1 cc (10,000 units). It ia swisH^
around in the mouth for a fuU five minutes daily, for seven or more days. All other antibiotics
are stopped. A one percent Gentian Violet solution may also be applied b.i.d. to the lesioiis^ but
the messy staining properties of this solution have decreased its use.
Herpetic Lesions. Fever blisters and cold sores caused by the hei^es silttplex wus begin with
a vesicle that, unlike the aphthous ulcer, usually involves tiie gin^va; tbe vesicle breaW and
forms an irregular ulcer. These lesions are most commortlfter a febrile ittness, trauma, actinic
exposure, or stress.
Treatment is symptomatic with nonirritating mouthwashes and oral irrigations; mild
anesthetic ointments and solutions may be helpful. Benzoin and Orabase may protect or dry the
vesicles and ulcers. Eafly application of Stoxil ointment or ether has been used, but flie success
rate is variable, and there is some suspicion of RNA alteration to a carcinogenic j^te.
Corticosteroids are contraindicated.
Aphthous Stomatitis. Recurrent canker sores are found most often as multiple, well-
delineated shallow ulcers on the buccal and labial lAucoia, tongue, soft palate (including
tonsillar pillars), and pharynx; occasionally, there is only a ingle lesion. These yellow-gray,
membrane-covered ulcers heal spontaneously in one to two weeks. There may be severe pain
requiring topical and oral anesthetics for eating. Longer relief can often be obtained by cleaning
the lesion off and applying Kenalog in Orabase, while it is still dry. This may be repeated three
or four times daily. Some physicians advocate the use of Tetracycline suspension, 250 mgm/per
tsp., held in the m^ouWi for at least two minutes and then swgjlowed, four tfanes 40y- Aphthous
stomatitis should be ©ferentiated flrom the herpetic gingival stomstitis 1^ l^ek of hle^ or
vesicle formation or associated systemic disease, before cortisone treatment is started.
Pharyngitis Sicca or Chronic Dry Throat. The pharynx is usually diy, smooth, and
shiny, with some yellow-greeft crusts. Treatment usually provides only temporary relief,
but 50 percent potassium ioWe, 10 gtt. in mflk t.td., SSKI, 6 gtt. in half a glass of water
ti.d., or piling tiie throat with Mandet's solution may be helpful. Occasionally, thr^e to
five grams of ammonium chloride t.i.d. also helps, but fluid and electrolyte balance must
be watched.
8-45
U.S. Naval Flight Surgeon's Manual
Pharyngeal Infections. It is sometimes difficult to determine if a pathogen is responsible for
an mfection in the nose or lltrofit, ot which pathogen is responsible. Many organisms such as
Streplociicms veridans Neismria, emaenobie streptococci. Staphylococcus atbm, or yeast are
always present and termed normal flora. Although a culture, which takes 24 to 48 hours to
grow, may be helpful in treatment and should be obtained, it should be remembered that
staphylococci can be obtained from 60 to 80 percent of the population, and beta- streptococci
are often isolated from patients with a viral infection. Furthermore, pathogens may become
e|iiM>lished in the host and remain for months without causing disease. This is referred to as a
cakiCT slate, in treatment, the physician must make an intelligent "^ess" ahout the etiolo^ of
the infection, using the most impurlant clinical picture, a smear from the infected area for pus
cells and predominant organisms, and then correlate this information with the bacteriological
findings.
Acute TonsiBitis. Acute bacterial tonsillitis or pharyngitis is most often caused by
beta-hemolytic streptococci, Group A. It usually has a rather abrupt onset, with fever of
I01°F+ and chills. The mucosa is grossly inflamed, with white or yellow exudate on the
lymphoid follicles. If the exudative tonsillar tissue becomes necrotic, it is termed necrotizing
tonsillitis.
The antibiotic treatment of choice is penicillin, most often given orally, 250 mgm, q.i.d. An
initial I.M. dose of 1.2 to 1.5 million units of procaine penicillin may be given to adults, to
obtain a more rapid blood level. Therapy should be continued for seven to ten days.
With toxic symptoms, the patient should be on bed rest and forced fluids. Hot throat
irrigations hourly or at least four times daily, coupled with analgesics, such as Empirin
Co)tn|ioand #3, Ascodeen — 30, or Tylenol #3, are necessary for both comfort and a more rapid
Infection of the Ungual tonsils at the base of the tongue, often not properly diagnosed
without the aid of the laryngeal mirror, may cause considerable dysphagia. Besides the normal
treatment for tonsillitis, the physician may need to add, by direct application, gargle or spray,
soothing substances such as Chloraseptic solution, MandePs paint, or a topical anesthetic, such
as Dydone, 0.5 percent or 1 percent.
Nasopharyngitis. Occasionally, a physician may see a patient who appears toxic and
febrile, with pressure or pain in the ears, a severe headache, or retrobulbar pain. Usually, the
oropharynx is somewhat inflamed, and there is occasionally neck stiffness or edema of the
uviihi. Examination of tiie nasopharynx with a mirror wiU make the diagnosis of
846
Otorhinolaryngology
nasopharyngitis with the discovery of exudate in upper reaches of the nasopharynx. Treatment
with LM ./I. V . antibiotics initially , plus supportive treatment, is advoeated.
Viral BiaryngitiS. Sor© throat, lymphoid injection without exudate, general or f»osterior
cervical adenopathy, and malaise are the usual symptoms of a viral pharyngitis; a normal white
blood count with increase in the lymphocytes is often the blood picture. Tonsillitis that has a
membranous exudate, marked lymphoid hypertrophy, often a negative throat culture, and does
not respond to penicillin, should be evaluated iot infectious mononucleoas. Diagnostic teste
include white blood count, differential, and a mononucleosis spot test.
In areas of frequent cases of gonorrhea, resistant or unusual cases of pharyngitis should be
cultured, specifically for Neisseria gonococci.
Thomw^dt's Disease. Physicians should be aware of a nasopharyngeal bursa or pouch that
sometimes forms in |h,^ jg^tKsae of the adenoid tissue and, when it becomes infected, produces
occipital headaches and an irritating, purulent postnasal discharge; it can also be present after
adenoidectomy. Diagnosis is made by ruling out sinus disease and visualization of the draining
bursa with the nasopharyngeal mirror, or, more clearly, the nasopharyngoscope, or Yankhauer
scope. Treatment requires either electrocoagulation or surgical removal of ihe cyst or pouch.
Perttomiltar Abscess. Known also as quinsy (sore throat), this abscess results when tonsillar
infection spreads or breaks through posteriorly into the potential areolar space between the
tonsil and the superior constrictor of the pharynx. Formation of the abscess results in
displacement of the tonsil toward the midline, anteriorly and downward, with displacement of
tb'e uvula to the opposite side; it also causes fullness or cellulitis of the soft paSate. There is a
variable degree of trismus, pain referred to the neck or ear, variable adenopathy, and often the
classic "potato" Speech, tiiiat mmiiM from iie spasm or cellulitis involwng the pharyngeal
muscularity.
Treatment consists of High doses of Systiemic antibiotics for 10 to 14 days and m:cision md
drainage (I & D) of the abscess immediately, if Hjlctuant, or as soon as fluctuance develops. If
spontaneous drainage is noted from a necrotic site, gentle suction and blunt, careful widening of
the opening assists in providing adequate drainage. Hot saline throat irrigations every few hours
and adequate analgesics are necessary for the first few days. The I & D site should be reopened
in 24 hours. Occasionally, a second or third I & D maf be necessai^ if considerable pus
continues to accumulate. Emergency tonsillectomies are performed by some physicians as a
treatment for the abscess, but this should only be done by experienced hands because of the
danger of bleeding or sepsis. It is advised .that an elective tonsillectomy be performed in about
six weeks, after the acute infection has subsided.
8-47
U.S. Naval Fli^t Surgeon's Manual
Incision and Drainage of Peritonsillar Abscesses.
1. Equipment
a. Long handle, cun'ed Ke% forceps with smooth blunt tips-
fa. Suction machine with tonsil and/or nasal suction tips
c. Long knife handle with #15 blade
d. Large metal basin
e. Culture tube.
2. Anesthesia
a. Premedication with I.M. Demerol/Vistaiil or L V. Valium is recommended.
b. Topical Cetacaine, one percent Cocaine, or four percent Xylocaine is helpful.
c. Local inMtration at the incision sit^ tvith dental two percent Xylocaine and
epi^i^pitritie, 1:100,0{)0, is often used, but some physicians are against iiiMlration
mto ceUulitic tissue.
3. Brocediipe . -
a. file best site for incision is at the point of intersection of a vertical line from the
last molar tooth on the involved side and a horizontal liifie^om flid lower edge of
the soft palate |ofi the opposite^ uidnv^olved sidei Ibe i^cira^m^^^^^
lateral toward the midlme, sAftM 1.5 to 2 cm loii^, jtik#n^i^(^^^^i^^
b. TTie curved Kelly is ioli oduced into the ineision fg^ E^fead,! opening over the fop,
but never through ,, tlu; tonsil. The tip is at first directed 8t»aight m, then sli^tly
downward and medially .
c. When the abscess caxity is opened, there is a sudden, often fbrci^l, release of thick
pus, for which both the physician and the patient should be prepared.
d. With the patient leaning slightly forward, immediate, rj^id, but gentle, suction is
applied to the draining pus and inci»on site,
e. The incision must be opened sufficiently. Bleeding is usually slight and clots form
in five or ten minutes. A sterile nasal suction tip may be inserted uito the incision
site for better evacuation of the pus, but strong aiction should not be applied, as
this may create severe hieediilg,
f. Hot saline irrigations, tliree or four times per day, are recommended. One or two
liters of saline are used for each irrigation. The solution can be used directly from a
commercial container or mixed by the pharmacy. Murphy drip bottles, irrigation
cans, or the solution bottles connected to I.V. tubing are placed eight to ten feet
848
Otorhinolaiyngology
high. A small oral irrigation tip or glass or plastic eyedropper can be used to
deliver a forceful, narrow stream. The solution should be as hot as tolerable
wiiftout burning the oral tissue.
Laryngology
There are four major functions of the larynx — airway, spuincter, protection, and
phonation. .,
As an airway, the vocal cords are constantly regulating tiiie reijuired air flow needed by the
lungs and maintaining a proper rifsistance or back prespuje.- >
When we strain or lift with our arms and chest muscles, the vocal cords close, trapping air in
the chest cavity, fixing the chest wall, and allowing for maximum efficiency in the lift. This
function comes into play for Ihe cough and for the effort in defecation.
The larynx is said to be the "Watch Dog of the Lungs." Through the sensory branches of the
superior laryngeal nerve, foreign bodies, abnormal mucus, pus, or fluids are prevented from
entering the trachea by the rapid closure of the cords, followed by cough or clesaing of the
throati I
The vocal cords produce ^ound which is modified by the lips, teeth, tongue, and palate tp
form the speech or singing tones.
Diseases of the Larynx
Hoarseness. Hoarseness is defined as roughness or discordance in the quality of the voice. It
is apparent that it is a symptom and not a disease process in itself. Often, the first and only
danger signal of serious disease, local or systemic, involves this area. Unfortunately, the degree
of hearseness presents no clue to the type of illness or its prognosis. A thorough examination is
necessary in all cases to ascertain the exact cause and to preserfbe thfe pktpet triaWJBilt.
Generally^ th«ife am inttinBic lesions such as inflammation, benign or malignant neoplasms,
allergies, and trauma. There may be disturbances in innervation, either central or peripheral.
Hoarseness may be a manifestation of system disease, such as TB, syphiUs, muscular dystrophy,
arthritis, or endocrine disorders, and finally, psychosomatic involvements must be considered
when all else has been eliminated.
Acute Laryngitis, The chief symptoms of acute laryngitis are pain aand hpai^ness, and they
may be secondary to an upper respiratory infection, most often viral, or the hemophilus in
849
U.S. Naval Flight Surgeon's Manual
children or streptococcus in adults. On laryngeal examination, the vocal cords and adjacent
kibg^ottic and arytenoid area are inflamed, and there may be various degrees of sweUing.
In most cases, treatment of the primary iUness with appjropriate antibiotics, cough
suppressants, steam inhalation, elimination of irritants, especially tobacco and alcohol, ^d
voice rest, is sufficient. Lozenges such as Cepacol, anesthetics, troche with benzocaine, or throat
sprays such as Larylgan, may be soothing. Laryngitis from vocal trauma and noxious gases is
Ipst'^atc^ with voice rest and huinidi^cation. Thermal bams or caustic injury may require, in
addition to .the other treatments, system steroids and tracheotomy.
Chronic Laryngitis. Chronic laryngitis includes many different condition^ and imphes
longstanding inflammatory changes in the mucosa, as might be expected from recurrent acute
episodes, chronic improper use of voice (singers, speakers, and hucksters), and exposures to
conditions, such as dust and fiim^s. Smoking and alcohol have been shown to
GOtttiibute, as well as TB, syphilis, and chronic sinusitis or bronchitis. Chronic laryngitis may
take the form of small, bilateral vocal nodules or largepolyps at iJhe junction of the anterior and
middle third of the vocal cords. Other forms are hypertrophic or hemorrhagic changes on the
cord or dry thickening of the interarytenoid area. Vocal activities must be Hmited and rest
encouraged. Surgical measures will occasionally become necessary. The Flight Surgeon should
esidtifirage the patient to keep well hydrated. Expectorant drugs, such as potassium iodide or
itntnonium chloride are advocated, as is the use of hiunidifieation. The Fli^t Sui^on should
follow the patient closely by regular internal minor laryngoscopy to assure early treatment
^ould suigical pathology develop.
Salivary Glands
CalcuU occur more frequently in the submaxillary duct and gland. A common sign may be
|iainful swelling of the glands when the patient eats. Locabzation of the calculus can often be
t6^^ by bimanual palpation of the ghind or duct, along the floor of flie mouth, and a dental
X-ffty of the floor of the Moulli. If the calculus is in the duct, it can often be milked toward the
papilla. Removal is facilitated, after local infiltration with Xylocaine, by cutting off the papilla
to enlarge the orifice and then slitting along Wharton's duct. Calculi in the proximal duct or
^and may require excision of the gland if the obstruction cannot be relieved. Infection behind
tfie obstruction usually responds to drainage but may require antibiotics as in sialadenitis.
Amte S^b^enitkt, Itie parotid is more often affected than the submaxillary gland, usually
H^titig "from retro^ade extentioh of the mouth infection and dehydration, especially in the
The duct ^ould be nnlked and a culture t«tet;. hbwever, the most common
Ofgatusin fe eit^n a penicillin-resistant, coagulase-positive stf^hylococcus. The empirieal
8-50
Otodiinolarjragology
choice of antibiotics would be adequate doses of cephalothin or methiciUin. Correction of the
dehydration is essential, and x-ray of 400 to 600R may be helpful in the treatment of pain and
swelling. In severe resistant cases, I & D of the gland may be lifesaving.
Otroniis Sialectesis. Kecurrent inf<BctidXis at, occasionally, congenital anomalies lead to stasis
of secretions and chronic lotion of the ducts and alveoli, which can be diagiio^
sialography. Long-tonn ^eari^y m&t tetracycline is often helpfijii but unresolved ^fni|t^M$
may necessitate excision of the affected gland. . , ^, '
Auriculotemporal Syndrome. After parotidectomy or injury to the gland, the patient may
experience gustatory sweating, called Frey's Syndrome. Temporary relief mi^t be obtained by
Scopolamine, but more lasting results may require a tyngj^nic neurectomy of JaBolfi^dn^e ji^^
and the chorda tympani nerve. . v • .
-I
8-51
U.S. Naval Flight Sm^n's Manual
SECTION B:
AUDIOLOGY
Hie Physics of Sound
iound is a remarkable phenomenon. It enables us to communicate with each other> to learn
new ideas, to influence others, and to enjoy Uh. It is intrinsically involved m hum^ aeMtity.
Without it, we would withdraw socially; too much of it, and our sense of hearing would be
dulled.
, The science of sound,: acoustics, provides a basfe for understanding hearing and
eommunications. Sound can be descxibed as a wave-hke pressure fluctuation in air that conveys
energy from the source outward in all directions. Sound can also be transmitlsid by fluid Of ktMd
media, but for simplicity, this discussion wiU consider only the m medium. Sound is also that
which is perceived by people or the human brain, so it will be necessary to describe the dual
nature of sound in terms of its physical and physiological characteristics (Table 8-7).
Table 8-7
Parameters of Sound
Physical
Psychological
Approximate
Human Range
Frequency (Hertz)
Pitch (Mel)
20-20,000 Hz
Intensity (Decibel)
Loudness (Sone or Phon)
Q-T20dB
Spectrum
Quality
oo
The basic physical characteristicg of sound are its frequency, intensity, and spectrum.
Frequency, measured in hertz (Hz) or cycles per second (cps) is the number of positive or
negative pressure fluctuations of a sound wave each second. Frequency largely determines pitch,
although it is not quite a one-to-one relationship. The subjective term pitch comes from the
musical vocabulary and is the relative lowness or highness of that attribute of sound relating to
the ftequencies of the musical scale. The gross frequency range of human hearing for young,
healthy, and undiseased ears is from below 20 to over 20,000 hertz.
The intensity of a sound is the term generally used to describe the amplitude component of
a sound wave. Intensity is not actually measured; sound pressure is usually measured, and its
level is related in decibels (dB) to an arbitrary reference pressure. Thus, the term sound pressure
kvel (SPL) denotes the measured sound pressure and is defined according to the following
equation: SPL = 20 log P/Pq dB, y/here P represents the measured rms pressure in Pascals (Pa),
8^52
n
and P^is the reference pressure in Pascals. The decibel is, then, a dimensionless logarithmic unit.
The reference pressure used by acousticians is 20 fiF a (or and wiU be used
throughout this chapter. AU sound level meters will be calibrated to this reference pressure.
Loudness is loosely related to intensity, depeiiding somewhat upon frequency and spectrum.
Much of the Uterature of psychoaeow^sg deals with the detailed description of this ejE>i|^tip
relationship. , •
The basic curves (Figure 8-12) showing equal loudness versus frequency at different levels
were originally developed by Fletcher and Munson in 1933. Sound level meters contain a set of
frequency-weighting networks which correspond to different loudness levels. Thus, the
A-wei#ited level, L^., corresp(|'|*|i to. «»» iipsl JipitomwilliaW a©«f thr«#iefl|l, the; B-we^toi
level, Lg, to a inoderale loudness level (55 to 88 dB), and the C -weighted level, Lq, is nearly
"flat" or unwei^ted and corresponds to loij^^|j^,sejpjBitipi^^vfi454B* > n i .
20
100 1000 5000 IQPOO
FREQUl^ t*i4'et(fli» f^'*§i;C0Nft (H z)
«.iC,IJ. [.r 0,lBC,HE,F,0.».*<:.l>.E.F.S.».=it*M=.«.B.":iI!|E.f.'.«.!t=.^E.r. C,«,S.C,I),E.F, S.i.B.C,
anrpspipimiiiipiffl-OM
Figttfe 8-12. Free-field equal -loudness contours for pure tones (observer faeing source)
determined by Robinson and Da^on. Piano keyboard helps identify the frequency 8cale.
Only the fundamental frequency of each piano key is indicated (Peteraon & Gross, 197S,
published by peemtesion of 6«nBad, lAe«).
r)
8-53
U.S. Naval Fli^t Siirgeon's Manual
The useful amplitude range of human hearing is froM 0 tol20 dB. fhe *ft«sftoM of heairo^
is the minimum level of sound that evokes a response in at least 50 percent of the trials. Hearing
sensitivity is the general term denoting the ahsolute hearing threshold of an individual. Hearing
acuity is the just-noticeable-difference in a controlled change of frequency, intensity, or
spectrum. Masking is the process by whidh the tiireShold of audibility of one sound is raised by
the presence of another (masking) sound.
The type of sound used most widely for hearing testing is a discrete frequency stimulus
called a pure tone. Most sounds, however, are complex mixtures of various frequencies and
intensities. In order to identify and to classify these complex sounds, a frequency analysis is
obtained which, when graphed, results in a spectram analysfe cattvfe.
A sound spectrum may, for example, be composed of most audible frequencies and would
be called broad-band or wide-band noiac. A sound with a few closely related frequencies would
obviously be called narrow band. Noise having all frequencies with equal energy is called white
noise, and noise with a gradual decrease in amplitude of the higher frequencies is called pink
noise. Musical sounds^ when analyzed, produce line i^eefra mnce they are composed of
fundamental fretjuen©ie9.and overtones or harmonic frequencies wblch are arithmetically related
to the fundamentd.
The sensation of complex sounds is rather difficult to describe. We are probably able to
distinguish complex sound patterns by repeated exposure, and we store auditory "images" and
patterns of changing spectral and temporal components. The more the repetition, the finer is
the ability to make subtle distinctions, e,g., the difference in Ijke sound quality between a
Stradivarius and a Guarnerius violin.
The graph in Figure 8-13 is a composite which brings together various levels of hearing and
tolerance throughout the audible range of hearing. The sound pressure level scale extends from
below 0 dB to over 160 dB SPL and has as its reference 20 jiiPa. The minimum audible field
(MAF) curve is the absolute threshold of hearing versus freqitency and is the same as tfie 0 dB
loudness curve in Figure 8-12. This curve is also very nearly 0 dB on the audiometer. Notice that
the ear is less sensitive between 3000 and 4000 Hz. Below 18-20 Hz, we feel rather than hear
the vibrations in the infrasonic range. Above 20,000 Hz, we sense a sort of pressure for sound in
ibe ultrasonic range.
The speech area ranges from 80 to 100 Hz to around 10,000 Hz and from about 40 dB to
80 dB SPL. Telephone and aircraft radio systems, however, are designed to transmit mainly the
frequency range from 300 to 3000 Hz. At levels around 120 dB SPL, many individuals find that
they can no longer tolerate the noise and will try to get away from it or seek hearing protection.
8-^
OtBihinblaryiigology
Note thit ftii is SO dB istbovfe iie lo^er level for the damage risk criteria (DRC) for the Navy
Hearing Conservation Program (Section ffl) based upon an eight-hour workday. At 130 to
140 dB SPL, many people describe sensations of pain or tickle in their ear canals. At
160 dB SPL, tissue damage has been observed in deaf subjects, viz., a bruising of the capillaries
of the tympanic membrane particularly around its periphery and near the manubrium of the
malleus.
50
100
ajo soo logo
FREQUENCY IN Hi
10000 SOOOQ
Figure 8-13. Thresholds of hearing and tolerance
(adapted from Peterson & Gross, 1972, published by permission of GenRad, Inc.).
-U +
Measurement of Hearing
Introduction
An individual having a significant hearing deficit may be identified through a simple
audiogram done during a physical examination or as a part of the Hearing Conservation
Program (HCP). After this identification, a mSotie MMM dMcal evaluati&l li*%iri^^4^
The e&Heal measurement of hearing and the interpretation of findings resulting from
such measurements has become progressively more sophisticated since the end of
WoridWarll. A whole new professional field involving measurement, diagnosis, and
rehabilitative aspects of hearing impairments has arisen since that time. The field is called
audiology.
U.S. Naval Fli^t Surgeon's Manual
Civilian audioiogistfi are employed at the Navy's two Aural Rehabilitation Centers (Oakland
and Philadelphia), at other major naval hospitals (e.g., San Diego), and at the Naval Aerospace
Medical Institute (NAMI) and the Naval Aerospace Medical Research Laboratory (NAMRL).
AXthm^i the Air Force and Army have military audiologistB, the Navy has none.
In places where there are no civihan audiologists, the bulk of the clinical testing function
would be assumed by an ENT technician, and interpretation of findings and subsequent referral
would be the responsibility of the otolaryngologist. Unfortunately, an ENT technician is often
not available, and the task falls to an audiometric technician or AVT. In the worst case (all too
frequently encountered), a general duty, junior corpsman with no formal academic or practicum
training is charged with the hearing testing task.
As is evident from the foregoing, the quahty of audiometric testing can vary greatly. For
this reason, the Fhght Surgeon must understand the basic concepts of hearing measurement and
be reasonably proficient in interpreting audiometric findings.
Basically, there are four reasons for obtaimng hearing measurements (audiometry): (1) to
aid in medical diagnosis of an existing problem, (2) tO plan a rehabilitation program,
(3) physical evaluation for admission or retention in a particular program or task area, and
(4) for hearing conservation purposes. The first area mentioned above is the topic of this
discussion.
Badc^ound
The term decibd (dB) is routinely used in reporting the results of hearing testing. When used
for this puipc^, the dB is always referenced to a value called audiometric "zero," which
represenfe statistical averages of hearing threshold levels of young adults with no history of aural
pathology. The current standard is ANSI (American National Standards Institute) S3.6-I969.
An earlier standard, on which many hearing tests on older personnel might be based, is ASA
(American Standards Association) Z24.5-1951. The newer standard was adopted because it
W^re accurately reflects the hearing of people today and is in substantial agreement with the
J$0 (International Oi^anization for Standardization) R389-1964 i^Commettdatioli. I%e ASA,
ISO, and ANSI average minimum audMe pressure curves are shown in Figure 8-14.
Note that the values are plotted in dB Sound Pressure Level by frequency. The numeric
values for each data point and the difference between the two standards are shown immediately
above the gr^h. AU of the ANSI tiureshold vidues are smdler (lower SFL) than their
corresponding ASA values. This is a result of better subject selection, better electro-acoustic
equipment, and better sound isolating booths for testing. The term audiometric "zero" is
8-56
Frequency (Hz)
125
250
500
1000
1500
2000
3000
4000
6000
8000
ASA Z24.5 (195T)
0 dB Hearing Level
3 1 mO
39.5
24.1
17.2
18.0
18.0
15.6
14.3
19.5
26.8
ISO R389 (1964)
0 dB Hearing Level
42.8
24.5
10.1
7.2
8.0
7.1
8L3-
mo
r 15.3
ANSI S3.6 (1969)
0 dB Hearing Level
45.0
25.5
11.5
7.0
6.5
9.0
10.0
9.5
15.5
13.0
ASA-ANSI
6.8
14.0
12.6
10.2
11.5
9.0
5.6
4.8
4#
60r
50
i|40
-I u
£ £
" Pi
g I 30
i £
<S S 20
10
o= ASA Z24.5 (1951)
□ = ISO R389 (1964)
x = ANS1S^8§^)
_i_
J-
100
250
500 1000 2000
i FREQUENCY IN HERTZ
4000 BCm 8000
-* f
*i -
> o ...
Figure 8-14. Audiometer reference threshold pressures
for TDH-39 earphone sound pressures re: .0002 microbar as measured in
U.S. Naval fli^t Sin^n^ Manual
applied to each of these values. For example, tfie average hearing fcEeahoM level (HTL) at
1,000 Hz for the ANSI standard is 7.0 dB SPL; this is audiometric "zero" for that frequency.
The same holds true for 6,000 Hz for the ANSI standard, where audiometric "zero" would be
equal to .15.5 dB SPL. It is this way of specifying audiometric "zero" that permits the use of a
straight line for "zero" on the graphic-type audiogram form (Figure 8-15). AH Navy
audiometers are now calibrated to the ANSI-1969 standard.
If both ASA and ANSI audiograms appeared in the medical record of an individual whose
hearing has not changed, it would seem that hearing had gotten worse. This is due to the
cttfferent audiometric "zero" standards and not to any organic change in HTLs. To convert the
ABA audiometric findings to ANSI, one would add the difference values in Figure 8-14 to
^oduce an audiogram direc% eota^aMe to the ANSI findings. The Fli^t Surgeon ^ould he
alert to this occurrence so that inf^tpropriate referrals are not made.
Another type of report format found in the medical record is the tabular audiogram
(Figure 8-16). This is simply the numeric presentation of HTLs by frequency. One also
ftequently finds a graph-type audiogram card in the medical record produced by self-recording
audiometers (Figure 8-17).
These audiograms are very often done as part of the hearing conservation monitoring
program. A self-recording card should not be left in the record. The HTLs should be transposed
to a serial, tabular form which should be a permanent part of the medical record. This greatly
facflitates comparisons of cunsent and previous audiometric results. Most frequently, testing
done at naval hospitals would be reported in the ^aph format (Fi^re 8-15).
The instrument used for more advanced hearing testing is a clinical pjr diagnostic attdlipmeter
(Figure 8-18). It very often is a two-channel unit and combines pure tone and speech
audiometry in a single cabinet. The two-channel capabflity permits the presentation of a
different stimulus to each em ^altaneoudy or "mixing" two stimuli for presentation to the
same ear, etc. There are many potential combinations. In the latter case above, one may wwit to
"mix" speech and noise to present to one ear. The two stimulus Mnh (amplitudes) can he
controlled independently, so that a positive or negative signal-to-noise (S/N) ratio can be
created. This is often done in testing speech discrimination ability. Presenting speech and noise
together makes the test much more realistic than presenting speech in quiet. Clinical units also
have provisions for microphone, tape, phono, or Internal oscillator input for pure tones. These
inputs are fed throu^ an attenuator and amp^r and ttien to the ou^uft transdu^r^ch
would be an earphone or bone conduction vibrator (Figure 8-19), but it coiild be one or even
two speakers.
8-58
NAVAL AEROSPACE MEDICAL RESEARCH LABORATORY
ACOUSTICAL SCIENCES DIVISION
AUDIOMETRIC REPORT
NAMI 6120/4 (Rav. 5-7S)
NAME.
AGE-_
-SSAIsr:!::
Audiomstric
W*b«r
^ L R ^
^SEX FACILITY-
.EXAMINER.
PURE TONE AUDIOGRAM^ ^ , .j
Fraquancy in Haiti
AUDIOGRAM CODE
-:iaATi-
126
250
eoo
1000
2000
4000 8000
0
10
m
w—
20
in
z
<
30
CD
'0
40
c
•
50
i
n
60
1
70
c
h
ei
80
c
•
90
I
100
110
?50 1600 >
PURE TONE MASKING^ '
Wide Band O Narrow Band □
r *
TOna CfVcav Titt^
SIS I Tatt:
Fraquancv
mm
Ear
Air
Bone
Un-
Masked
Masked
Un-
Maskad
Matked
R
0
>
>
Red
L
X
<
<
Blue
SPEECH AUDIOMETRY
Masking
L
R
SF
LV or
Rac.
SRT
PB
%
PB
Level
MCL
UCL
'MMtfr^ f
I igallbt^lorr R«f,
ABBREi|nATlONS
PTA
PB
BiSk^y Type:
TyVripinogram — ■
ME Prataura —
naflax Decay — .
ME Peflax —
PIMT — Did not test
NR or — No response
SF - Sound field
MCL — Most comfortabla
loudness
UCL - Uncomfortable
loudness
SRT — Speech reception
threfhoM
AC
BC
LV
. Pure tone aver.
S0O-2OQO Hz.
' Phonetically
balanced word
lists
- Air Conduction
' Bona Conduction
- Live Voica
SgitMtura of £xamin«r
Fixate 8-15. Graphic audiogram form.
859
U.S. Naral E^i^t Siu^eon's Manual
HUftm RECORD V
nm emis (rev. t-ta)
AIR CONDUCT t ON
I
2000
BONE CONDUCTION
' RIGHT
500 TOOO ;0OP 3000 40PO
OPPOSITE EAR MASK AT
SCHWA BACK
500 1000 gPOO 3000 AQOO ''^
SPEECH HFCEPTION
CATE
SPOND.
OTHER
MIC.
REC,
DATE
SPOND.
OTHER
MIC .
REC.
R 1 GMT
R IGHT
LEFT
LEFT
FREE
F lELH
FREE
FfELD
C*T£
Pb AT
li
MIC.
REC .
EXAMINER
DATE
Pb AT
%
Mit
REC.
EXAMINER
1 ■
RIGHT
RIGHT
LEFT
LEFT
FREE
FIELD
f RLE
FIELD
Figure 8-16. Tabular audiogram form.
8^60
OtorhinoIaryfigotQgy
AUDIOGRAM
Figure 8-17. Audiogram card produced by self-recording audiometers.
Figure 8-18. Clinical audiometer and sound-treated test suite.
8.61
U.S. Navsi Fli^t Surgeon's Msuiual
Figure 8-19. A lione-conduction vibrator
with a spring headband.
Clinical testing is conducted with the patient seated in a sound-treated room with the
examiner outside (Figure 8-18). The examiner can operate the equipment, whose output is
cabled through the sound room wall, and can observe the patient through a window. The noise
level inside an audiofflSetrie test booft is critical and is specified by the Americal National
Standards fostitute. The subject responds, in the case of pure-tone testing, by either pressing a
button, which triggers a response light on the audiometer, or simply by raising his hand. For
speech audiometry, the subject responds by writing or checking off the word identified or by
repeating the word aloud after the examiner. There is provision for tsvo-way communication
between patient and examiner,
Basic Hearing Tests
Pure-Tone Audiometry. The most common and also the most elementary test is done with
pure tones. The patient is asked to respond whenever he heats a fen©, r^jo-dle^ of the loudness
of the signal. The lowest amplitude at which the patient responds at a particular frequency is
called the hearing threshold level (HTL). HTL's are determined at octave frequencies from
250 to 8000 Hz and at the half -octave frequencies of 3000 and 6000 Hz. Each tone is presented
for a period not exceeding one second. There will be several tone presentations at a particular
fi'equency before tiie HfL h recorded on the audiogram (Figures 8-15 and 8-16). In general,
pure-tone HTL's are determined for both air conduction (earphones) and bone conduction
(vibrator) stimuli.
8-62
Otbtbificilaiyngologf
Masking noise is used when one ear needs to be isolated from the other in order to get a
correct threshold measurement on the test ear. Masking noise is generated within the
audiometer and can consist of a broad or narrow -frequency band. Narrow band noise is most
efficient for pure-tone testing. In a situation where one ear of the patient is "dead," incorrect
information would be obtained on the nonfunctional ear if masking were not used on the good
ear. By air conduction measurement, the nonfunctional ear wouli^yigki ^L's around 50 to
60 dB. This is due to a phenomenon called "crossover." Even though the signal is presented at
the nonfunctional ear, it is heard by the good ear primarily by direct energy transmission
through the head from the vibrating earphone cushion. The head creates about a 50 to 60 dB
"barrier" between ears. If proper masking noise is applied to the good ear in the case
mentioned, then a correct determination of a profound hearing loss would he bade. ' '
An dtectromechanical vibrator is placed on the mastoid process for bone conduction (BC)
testing. The threshold determination procedure is identical to that of air conduction (AC)
testing. Since it requires more energy to drive a mechanical vibrator than an earphone, the
maximum hearing loss that can be measured for BC is less than for AC, e.g., 70 dB for BC and
110 for AC. Care^shoiridlie tak^a to place lhe^i5a*«#-0ef€ie mastoid-withWt contacting the
pirnia. This is to i^re iist reaponses *t low^jequ^fenelies are auditory and not tactile in nature.
Masking of tte feleatfiEito^id ear is done more frequently in BC than in AC. This is because
interaural attenuation, while about 50 to 60 dB for AC, is practically nonexistent (0 to 5 dB)
for BC. In the previous example of the "dead" ear, a BC measurement without proper
contralateral masking would have shown normal BC hearing in the nonfunctional ear due to the
low (0 to 5 dB) crosso^^J* I6<'eli.
Speech Audiometry. Another aspect of the hliii^'^lMi^lB^teeff 'is speech audiometry.
The purpose here is to dilcover two things. First, it is necessary to determine the amplitude at
which the patient can repeat back approximately 50 percent of the two-syllable words
presented to him. This measure is referred to as the speech reception threshold (SRT). There are
six word lists, each hst being a different scrambling of the same 36 words. The most widely
used form is CID Auditory Test W-1. Secondly, the percentage of 50 single-syllable words the
patient can correctly repeat back is determined. This test is called the "PB score" or "PB
Max" and is a measure of speech intelligibUity. The term "PB" stands for "phonetically-
balanced." When these word lists (24 lists with 50 words each, and 200 words in the corpus)
were developed in the late 1940's, it was believed that the phonemes in each 50-word Ust
had to have the same proportionate frequency of occurrence as that in everyday EngUsh, in
order for the test to be vahd. This was later diown to be unnecesssp^, but the feti|ijnt)iogy
'W' etifl reinaijis *)id|^. > ; ; - t . -
8-63
U.S. Nayal Fli^t Smgepi^^ Manual
A graph demonstrating the relationship between word discrimination and amplitude (SPL) is
shown in Figure 8-20. The various curves shown are called "articulation" curves. The PB words,
the most widely used form being CID Auditory TestW-22, are presented at a level ol 40 dB
^ve the SRT in routine use. Since this represents a supra-threshotd presentation, maskitig
iioise is almost always used in the contralateral ear. It is at this ampUtude or sensation level (SL)
ttiat most patients would achieve maximum performance. However, there are instances where
tHib % iidt tfli Case. So, ideally, an articulation curve should be generated by presenting the
Mohdsyltabic word ligti at a variety of senigation levels.
10 20 30 40 60 60 70 80 00 dB
SOUND PRESSURE LEVEL in a NBS-9A Coupler re: 0.0002 Dyne/On^
Figure 8-20. These typical word intelligibility curves demonstrate the relationship
between word discrimination and amphtude (Davis & SiHvempn, 1970).
Often speech discrimination testing is done in a noise background. A variety of word lists
and test formats are used for this purpose. The basic concept behind this is to provide a more
realistic environment in the measurement of speech discrimination. It is a rare occasion,
particttlarly in the naval envfarosment, when flie listening environment is absolutely quiet. There
we several considerations for discrimination in noise testing. Probably the most important,
single corijideration is the signal to noise ratio (S/N) employed in the test. S/N ratio is expressed
in dB, and ihe figure represents the number of dB the signal (speech in this case) is above or
below the level of the noise. If the IS/N is minus 4 dB, this would mean fhait the average speech
level is 4 dB below the noise level. Typical S/N levels used in discrimination testing tiiat would
be reflective of typical naval noise environments would range tiom 0 to +4 dB S/N,
W^^U TommemSf TesU.Tim last component of the basic test battery is the threshold
tDi^-debaf^ test (TDT). This is a pure-tone, supra-threshold test. It is usually done at 4,000 Hz
iirst, and, if positive, the test frequency is dropped by octaves until 500 Hz is tested. The tone is
8-64
Otod:tinola]*fiigology^
presented at 5 dB SL for one minute. If the patient can hear the tone for the entire period at
the same level, the test is negative. If the level of the tone has to be raised by 20 or more dB
above the starting level, the test is positive. The TDT is a measure of auditory adaptation and is
considered a screening test for retrocochlear pathology. If the test is positive, other, moiie
detailed, tests would be done in order to help esls&to the reason for the abnoJ*malfa^tf]^tett«
md the site of the lesion.
Advioiced Tiifii in Differential Di^oas
Short Increment Sensitivity Index (SISI). This is a pure-tone test^f^p^ntel at 25 dB Sh ti^St
measures amplitude digjsrimination abiUty. The result is expressed J||nns of percent correct
idpatiici^iioti out of twenty, one-dB increments, added to a reference pure-tone level. ,4^-^^
pe^cen^CO^^ect re8ponse> indjgajive of a 90(M^ . , ,
Alternate Binaural Loudness Balance Test (ABLB). This is one of two direct tests of a
phenomenon cdled recruitment. Recruitment is an abnormal growth of loudness in which soft
sounds are not heard while loud sounds are perceived to be as loud as in a normal ear. The
presence of recruitment narrows the dynamic range of hearing significantly and is characteristic
of a cochlear (sensory) pathology. In order to do this test, it is necessary for hearing to be
within normal Limits in the contralateral ear at the same frequency at which the test is being
done in the poorer ear. - •
Beke'sy Audiometry. B6kesy audiomelry is an advanced site-of-lesion test and is a special
fonn of the more routine, self-recording audiometry procedure. The patient is asked to track his
pure-tone threshold by means of a response button, first for a pulsing tone and then for a
continuous tone. Either a discrete frequency or continuous frequency tracing can be generated.
The audiograms are traced on the same graph, ttea«3fiq|fam !i fib'en typed according to the
relationship between the pulsed and continuous tracings, there are five mno^^^^^m pi
Bek^sy aufliog^s. Each typljll SHptpftive of a particular pathology and will be discussed m
the se©tlon on interpretation of fewHngs. '
Brain Stem Evoked Response (BSER) Audiometry. BSER audiometry and electro-
cochleography (ECOG) are two relatively new objective hearing tests. Both are eleeio-
physiologic measures of auditory function. These are noninvasive techniques that inv^ve
computer averaging of the auditory systems electrical response to ^Miks or tone pulses presented
by earphone. Either of these tests could be used in cases of functional hearing loss (malingering
or psychogenic problems). Beyond this, the FUght Surgeon should have Uttle contact with tests
of this type.
8-65
U.S. Naval FH^t Surgeon's Manual
Lengthened Off Time (LOT} Test. The LOT test is also used where malingering is suspected.
This is basically a Bekesy test with the period between pulses lengthened and unequal to the
duration.0f the pulse itedf, e.g., 800 msec off and 200 msec on. This temporal pattern magnifies
the difference between the pulsed and continuous tracings, making the identification of possible
malingering easier.
Sensitized Speech Tests. These are tests in which the auditory stimulus is speech that has
been altered, either in the amplitude, temporal, or frequency domain. They are used when a
central auditory disorder is suspected. "Central" is defined as a site of lesion somewhere in the
btaiiistem dr cortical auditory areas, Rire-tone tests are not mifficiently complex in nature to
identify these lesions. In general, as fhe site of lesion proceeds centrally in the auditory ^stem,
the tests to identify it need to btNCome more and more complex in structure. The 'tlight
Surgeon's contact with this type of test information would be quite rare in the active duty
population. It would more Ukely occur in the retired or dependent groups.
Itftpedance Audlomefry. This is actually a sub-battery of tests and is the audiolt^st's most
recent addition to the diaptostic armamentlriUm. Figure 8-21 shows a pictorid diagram of a
typical impedance audiometer.
PROBE TONE QENEftATfON
Sound
Generator
220 H
^ 220 \ T-!^
AIR PRESSURE
GENERATION &
ME ASUREMEN T
Air
Pump
O Intensity
Knob
Msnwnster
ompliance
Meter
Rectifier
Amp
OC Source
(18 VI
SPL8( COMPLIANCE
SENSING &
MEASUREMENT
Microphone |
(Sound reflecting off .
tympanic membrane I
to microphone pickup^
Figure 8-21. Major functional parts of the impedance measurement system
(Impedance Audiometers, 1976).
8-66
Otorhinolaryngology
This device measures various mechanical aspct^ts of the middle ear. Four general
measurements are obtained using the impedance audiometer. These are
1. stapedius reflex thresholds — ipsilateral and contralateral
2. static compliance — the inverse of impedance and expressed in cc
3. middle ear pressure — expressed in MMW
4. tympanogram — a dynamic plot of compliance as a function of externally applied
pressure.
A probe tip (Figure 8-21) is inserted into the test ear and an airtight seal is obtained before
testing begins. A standard earphone is placed over the contralateral ear. There are three holes in
the probe tip: one is to introduce a 220 Hz tome into flie space created between, the tip of the
probe and the tympanic membrane; the other leads to a microphone which meamres the SPL in
the space, and the third is used to introduce air into'lhe space (either negative or positive
pressure relative to normal atmo^heric pressure can be achieved).
Tympanograms are generated automatically by the machine and are recorded on an
associated XY plotter. From this plot, the middle ear pressure is obtained. The static
compliance measure is calculated from the difference in volume between the resting compliance
measurement and the measure taken with 200 MMW (equivalent) pressure. Stapedius reflex
thresholds are determined by introducing an acoustic stimulus at various amplitudes through the
earphone. When the ampHtude is high enough (70 to 90 dB SPL for pure tones), the stapedius
will contract. Since this is a consensual reflex that stiffens both tympanic membranes, it can be
monitored on the probe side. The contraction shows up as a change on the compliance meter
indicating lowered compliance, i.e., higher impedance.
In addition to defining middle ear problems, impedance audioraetjy can yield useful
information in helping to identify the following disorders: (1) acoustic neuroma, through the
stapedius reflex decay test, (2) facial nerve site of lesion, (3) Eustachian tube status, (4) fistula,
and (5) functional hearing loss, volitionally or psychogenicaUy based.
Interpretation of Hearing Tests
Hearing Loss Classification SysteniB
The three most frequently encountered types of hearing loss are sensorineural, conductive,
and mixed. A conductive loss exists because of a mechanical blockage in the auditory system.
The specific site of the problem could involve "flte pinna, extemd auditory meatus, the
tympanic membrane, or the middle ear cavity. A sensorineural loss reflects, in general, damage
to the cochlear nerve ceUs and fibers in the eighth nerve trunk. Throu^ differential diagnostic
8-67
U.S. Naval Flight Surgeon's Manual
testing, this type of loss could be specifically identified as sensory (cochlear) or neural (eighth
nerve trunk). A mixed loss is simply a combination of conductive and sensorineural
components. Table 8-8 shows fke ejEi^fioation ctitert* for llie three typm of losses. Note that
the criteria include only air and bone conduetioii HTL infortaation. All dB values are referenced
to audiometric "zero" except air-bone gap which is the dJB difference between air conduction
and bone conduction HTLs at any given frequency. A comparison of these HTL relationships is
made in Figure 8-22, utilizing the audiogram code (Figure 8-15). It should be noted that
Figure 8-22 indicates HTLs for only one frequency. In practice, HTLs would be determined at
aU frequencies shown on the audiQ^am.
Table 8-8
Pure Tone Audiometric Criteri^i
for Classification of Mixed* Conductive, and Sensorineural Impairments
Sensorineural
Conductive
Mixed
Air Conduction Threshold
Worse than 25 dB
Worse than 25 dB
Worse than 2S dB
Bone Conduction Threshold
Worse than 15cfB
Better than 15dB
Worse than 15dB
Air-Bone Gap
Les£than lOdB
More than 10dB
More than lOdB
SeiTsorineural
1000 Hz
Conductive
1000 Hz
Mixed
1000 Hz
m
T3
10
2Q
30
40
— <A
^> —
<
-> —
>
<
^
^
Figure 8-22. A comparison of hearing threshold levels
for the ^ree types of hearing losses. The ^rmbob are defined in Figure 8-15.
Classification of hearing by severity of loss is shown in Table 8-9. The average HTL or
pure-tone average (PT A) should agree with tiie SRT by ±5 dB in the greatest proportion of
hpuiog loss types. This relationidiip is very often used as an internal reliability check between
pure-tone and speech test results. Someone attempting to feign a hearing loss generally would
8-68
Otorfiinolaiyngology
have a much better SRT than would be predicted from the pure-tone average. A hearing aid
generally would not be considered for a patient, unless the loss had reached the "mild"
classification in the better ear.
Table 8-9
Classification of Hearing Impairment by Severity
Average HTL*
Qassificattpn
Abtlity to Urn Speech
0-25 dB
Not significant
No Difficulty Even With Faint Speech
25-40
Slight
Difficulty With Faint Speech Only
40-56
Mi>d
Frequent Difficulty With Normal Speech
55-70
Marked
Frequent Difficulty With Loud Speech
70-90
Severe
Only Hears Shouted or Amplified Speech
90 +
Extreme
Usuilly Carir«6t Understand Even
AmplFRed Speech
*Average Hearing Threshold Level (HTL) is the arithmetic mean of the thre^t^iis tW- PUCfitone frequencies of
500, 1000, and 2000 Heitz. Average HTL can also be referred to as the pura tone tmriMei (PTA). The PTA
correlates very highly with the actual speech reception threshold measurement. ,
(adapted from Davis & Silverman, 1970).
Speech discrimination scores are a bit more qualitative in their interpretation than are
SRTs. The general coMept is that in sensorineural hearing loss, the speech dfecitelff^
will be directly proportionttl to the degree of ^stem damage (cotMear hair d^ls or neural
fibers). There is no quantitative way to predict speech tliiSGi|(nination ability from the pure-tone
audiogram. Sensorineural hearing loss will be the most common hearing loss seen by the Flight
Surgeon. Most persons with sensorineural losses have greater difficulty with speech discrimina-
tion in noise than in quiet. This is because the noise further reduces their abiUty to hear
high-frequency consonants tvhidi carry the preponderance **f speech information. Also, these
patients may be very much annoyed by loud sounds (becauise of the recruitment phenomenon)
and make less than ideal candidates for hearing aid use. Discrimination scores of 80 percent or
better oil the W-1 lists are considered good, 60 to 70 percent, fair, and 60 percent and less,
poor. The naval aviator's speech discrimination test (NASDT) requires a minimum score of
70 percent for a passing grade. This is a speech-in-noise test and is given to establish a waiver
when pure-tone hearing standards are not met by the patient.
Differential Dia^osis
Advanced hearing tests are useful adjuncts to otologic diagnosis because they help
identify the focus of the hearing disorder'. There is no test accurate enough to do the job
alone. One should t^e advantage of the tacreased senaitivf^ inherit in the pattern of
^results ft-om a properly selected test battery. A very useful multiple test batteiy, described in
8-69
U;S. Naval Flight Surgeon's Manual
Table.8-10, consists of the SISI test, ABLE, and Bekesy audiometry. SISI and ABLE scoring
are, shown in the Table,
Table 8-10
Ideal Test Results for Each Locus
LjPCSUS
SISI
Bekesy Type
ABLB
Middle Ear '
1
N
Cochlea
+
II
Por C
Eighth Nerve
III or IV
N
Possible Test Results for Each Locus
And th^ Likelihood of Occurence
Locus
Likelihood
SISI
Bekesy Type
ABLB
Middle Ear
Disorders
In 67 of 100
In 14 of 100
?
1
1
N
IM
In 10 of 100
+
1
N
In 5 of 100
II
N
In 4 of 100
?
11
N
Cochlear
In SO of 100
+
II
C
Disqrders
In 25 of 100
+
II
N
In 20 of 100
+
11
P
In 5 of 100
+
1
P
Eightti Nerve
Disorders
In 64 of 100
In 18 of 100
III
IV
N
N
In 9 of 100
IV
P
In 9 of 100
7
IV
P
Mote: SISI scores are coded as follows: (-) =0to 20%, (?) = 20 to 60%, (+) = 60 to 100%.
Loudness Balance results ar^leMed as tollom: N • ho recrllfthifent, P - partial recruitmsnt,
C = complete recruitment.
(adapted from Jerger, 1962, published by permission of the American Speech and Hearing Association).
The four basic types of Bekesy audiograms are shown in Figure 8-23. Not all patients with
the pathologies indicated will display the specific type of audiogram shown in the Figure. In
fact, a certain percentage of subjects with middle ear disorders show Type n Bekesy tracings.
This is ^mrn in Table 8-10 to be about nine percent.
Johnson (1968) further demonstrated the necessity for a, test battery approach to diagnosis
with the Bekesy data on confirmed cases of acoustic neuroma given in Table 8-11. This data
8.70
Otoihinolaiyngology
shows that 61 percent of the patients produced appropriate tracings relating to acoustic
neuroma, while 41 percent produced tracings generally aasoeiated with eo(M@az aad itti#le ear
pathologies. Clearly, a test-battery approach is a necessity. The probability; erf error when
correlating several tests results rather than depending on a single piece of information is greatly
reduced.
20
3
I 40
60
80
TV
3e 1
1
c
Fnquency In cpt
125 250
500 IK 2K
Frequency in cps
20
9 40
□)
c
g60
X
80
125
m
■o
c
a
s
Z
1
250 500 IK 2K
Frequency in cps
4K 8K
1
Typ
e IV
-J—
f
%f
\
—
c
AAA
126 250
500 IK 2K
Frequency in cps
4K 8K
Figure 8-23. The four types of Bekesy audiograms: Type I occurs in normal ears and in disorders of
the midifle eai. Type II occurs in disorders of the cochlea. Type ffl and Type IV occur in disorders of
the eighth nerve (Jerger, I960, published by permission oi Journtd of Speech and Hearing Research).
Table 8-11
Bekesy Data for Confirmed Cases of Acoustic Neuroma
Percent Cases
Btkesy Type
24
IV
37
III
33
II
8
1
(data from Johnson, 1968).
8-71
U.S. Narat Flight Surgeon's Manual
Another category of Bekesy trace is the Type V. This is commonly seen in patients
attempting to feign a hearing loss. It has essentially a Type IV configuration, except that the
^mtinuous and pulsed tracing are reversed, i.e., hearing for the ^Utiftuotl^ tone is showtl as
being better than hearing for Uiiis pulsed tone. Perceptually, the loudness of a supra-threshold
tone is greater for a continuous signal than for a pulsed signal. What the patient is actually doing
is tracing an equal loudness contour for each type of signal. It should be noted that this test can
be done with some of the self-recording screening audiometers in the fleet. AH that is necessary
is to be able to select either a pulsed or continuous tone on the instrument. In a clinical setting,
the LOT test, mentioned previously, would be done and would in most cases accentuate the dB
separation between two tracings.
Impedance audiometry is becoming a routine tool in many naval hospitals and some regional
branch clinics. Figure 0-24 ilhistrates six types of tympanometric configurations. Shown beio^v
each one are the possible associated pathologies and the type identification for that particular
configuration.
Pb^fe Test Findings - Illustrated Cases
The audiologic findings in ten hypothetical cases are presented in Figul^ 8'25 ^ough 8-34.
Each. Figure represents typical audiologic findings related to the stated diagnosis. The cases are
arranged roughly according to the probability that the type of disorder would be seen by the
Flight Surgeon, i.e., the first case is most probable and the last case is least probable.
AH cases include pure-tone-and speech audiometric findings and identifica|ion of the type
and severity of loss (see Tables 8-8 and 8-9, respectively)* In appropriate instance, tone decay,
SISI, Bekesy, and impedance audiometric test results are shown (lower left of each Figure).
By studying the Figures and referring back to the information already presented, the FU^t
Surgeon should gain a good appreciatioti of tihe area of interpretation of audiologic results.
8-72
OtorhinolaryUgblogjr
c
(0
Q.
E
o
O
-200
..+200
-200
+200 -200
+200
Type A:
Normal
Type Ag:
Otosclerosis
Tympanosclerosis
Fixed Mallaus
Type Ad :
Flaccid Tympanic Membrane
Healed Perforation with no :
Middle Layer , 3
I I
u
c
a
E
o
o
-200
+200
Type Add;
Osgicular Disarticulation
-200
Type B:
+200
-200
+200
Type C:
Primarily, Secretory
Otitis Media
Adhesive Otitis Media
Tympanic Membrane Perforation
with Nonfunctional Eustachian
Tube
Negative Middle Ear
Pressure
Figure 8-24. Tympanometric configurations.
8-73
XS.S. Naval Flight Surgeon's Manual
NAVAL AEROSPACE MEDICAL RESEARCH LABORATORY
ACOUSTICAL SCIENCES DIVISION
AUDIOMETRIC REPORT
NAMI 6120/4 (Rsv. 5-75)
NAME.
AGE_
RANK/GS LVL..
.SSAN.
.SEX--i-F|iCILITY_
.exaMiner.
Auctiomatric
W«b«r
^ L R ^
12S
^BB TONE AUDIOGRAM
Fr«qu»ncv In Horn
AUDIOGRAM CODE
-DATE.
250
500
1000
2000
4000 8000
0
10
20
30
40
50
60
70
80
90
100
110
I —
e
)>-
— c
<)
1
Air
Bone
Esr
Un-
Masksd
MaskBd
Un-
Masked
Masked
R
0
>
>
Red
L
X
a
<
<1
Blue
SPEECH AUDIOMETRY
Mask Ins
L
R
SF
LV or
Rec.
SRT
5
5
Rec
PB
%
92
90
Rec
PB
Level
40
40
MCL
UCL
Maiking
3000
750 1500
PURE TONE MASKING
Wid* Band □ " : Narrow Band □
I L R Frequencv
6000
Wideband Noise □
Speech Noiie □
Calibration Raf
T^na Oacav Test:
SISI Tatt:
B^k^V Type:
TvnipenOBram — ,
ME Preiuira — .
naflax Decay — .
ME Raflax — .
Nea
JNea_
Pas
Pos
4000 Hz
4000 Hz
ABBREVIATIONS
PTA
PB
DNT — Did not test
NR or — No response
SF - Sound field
MGW Mott leomfortibla
loud nan
UCL - Uncomfortable
loudness
SRT — Speech reception
thrariiold
- COMMENTS -
AC
BC
LV
■ Pure tone aver.
500-2000 Hz,
' Phoneticallv
balanced word
lltti
Air Conduction
Bone Conductjop
Live Voice
Type. Bilateral, high frequency, sensorineural
DiaQnosis: Noise induced
Signatum of Examiner
Figure 8-25. Audiologit- findiiigs typical of noise induced bearing loss.
8-74
Otorhinolaryngology
NAVAL AEROSPACE MEDICAL RESEARCH LABORATORY
ACOUSTICAL SCIENCES DIVISION
AUOIOMETRIC REPORT
NAM1 6120/4 (Rev. 5-7S)
NAME.
AGE —
RANK/GS LVL.
.SSAN.
-SEX FACILITY-
.EXAMINER.
Audiomatrie
Wabar
^ L R ^
PUtttTOME ALTDIOGRAM
Ffaquancy in H«m
2§o nao 1000 ' zoob
AUDIOGRAM CODE
.DATE-
4000 8000
0
10
20
30
40
50
60
70
80
90
100
-e)
(
— ^
^<
•)
C
}
Ear
Air
Bone
Un-
Mssked
Un-
Mssk«d
Masked
R
0
A
>
>
Red
L
X
a
<
<
Slue
SPEECH AUDIOMETRY
Masking
L
R
SF
LV or
Rbc.
SRT
10
5
LV
PB
%
95
100
LV
PB
Level
45
45
LV
MCL
UCL
7S0 . 1B00
PURE TONE MASKING
Wide Band O
Torn Decay Ten:
SIS I Test :
B^k^sy Type:
Tympanooram —
ME Pressure —
Reflex Decay
M E Reflex —
Nafr6w Band □
L R
PNT DNT
3000
Frequency
6000
Marking ^^^^ ^
Calibration Raf
ABBREVIATIONS
PTA
DNT
DNT
V
ANT
A
A
0
0
DNT
DNT
100
95
SO
80
85
75
DNT - Did not test
NR or — No reiponta
SF - Sound field
MCL — Mott comfortable
loudness
UCL ~ Uncomfortable
loudnesi
SRT — Speech recaptioit
threshold
--COMMCNTB
Fungtianai — MailiriBiarJfig
PB -
AC
BC
LV
Purs tone euer.
BOO-2000 Hz.
Phonetically
balanced word
lists
Air Conduction
Bone Conduction
Live Voice
4000 Hz
2000 Hz
IPqO Hz
Signtitain of Ekamiher
Figure 8-26, Audiologic findings typical of functional hearing loss.
8-75
U.S. Naval Flight Surgeon's Manual
NAVAL AEROSPACE MEDICAL RESEARCH LABORATORY
AUDiOMttRie MePORT
NAM) €120/4 (R«v. S-tSY
NAME.
AGE —
, RANK/GS LVL.
.SSAN.
-SEX-
FACILITY-
.EXAMINER,
Audfomatric
Waber
R ^
ISB
PURE TONE AUDIOGRAM
-DATE.
260
sob
lOOb
"2000
4000 8000
10
20
30
40
50
eo
70
80
00
100
110
«
<
>^
)
(
E
3—
-E
Ear
Air
Bona
Un-
Maikad
Mask ad
Un-
Uaikad
Maitcad
R
0
>
>
Red
I-...-
*
CD -
<
<
Blua
SPEECH AUDtOMETRY
Walking
R
SF
LV Of
Rac.
SRT
40
0
Rec
PB
%
100
96
Rac
PB
Laval
80
40
MCL
UCL
-v-i ' ?eo MOO
PURE TONE MASKING
WldaBand □ Narrow r«rtd □
L R
Tona Decay Tatt:
SISI Taft:
B^k^iy Tvpa:
Tympanogram
ME Prastura —
Raflax Decay —
ME Raftax —
Nag
Nap
3000
Fraquancy
4t< Hz
6000
Maikina WWiband Noita □
iviaKing Spateh MDtia □
' Callbrvflon R«f
PNT ami
DNT
DNT
ABBREVIATIONS
DNT - Did not ta«t PTA
N R Of - No raiponia
SF -Sound flaw pb -
' Met. - M6it Gdrn<F&Mabt«
loudnan
UCL — U ncomf ortabJa ■ AC —
loudnatt BC —
SRT - Spaach racaptiOn LV -
thrathoM
- COMMENTS -
Typa; Unllataral, conductive
Pura tona avar.
BOO-2000 Hz.
Phonatlcally
batancad word
llm
Air Conduction
Bona Conduction
LIva Voica
A
B
0
Not definable
DNT
Absent
Absent All
Sevarltv: Slight to mild
Dlagnoals: Otitis media
SigfUture of Examiner
Figure 8-27. Audiolo^c findiiigs tf^pical ofonilateral otitis media.
8-76
Otorhinolaryngology
NAVAL AEROSPACE MEDICAL RESEARCH LABORATORY
ACOUSTICAL SCIENCES DIVISION
AUDIOMETRIC REPORT
NAM I 6130/4 (Rav. 6-76)
NAME.
AGE_
.SEX.
. FACILITY.
RANK/GSLVL..
EXAMINER.
.S$AN.
Aud iomstrie
Weber "
R ^
126
PURE TONE AUDIOGRAM
F requaney . Iri l4«rtt
AUDIOGRAM eODE
.DATE.
2B0
500
1000
2000
4000 8000
5
n
£
!
3
I
z
0
10
30
30
40
70
80
aO
100
110
^^^^
Ear
Air
Bone
Un-
Masked
Masked
Un-
Masked
Maiked
B
0
A
>
>
Red
CD
<
<1
Blue
SPEECH AUDIOMETRY
Maiking
R
SF
LV or
Rac.
SHT
50
48
Rec
Pfl
%
96
\R&L
80\
100
Rac
PB
Level
90
88
MCL
UCL
Mefklng
tSO 1600 3000
PURE TONE MASKING
Wide BarKt □ Narrow Band □
L R Freqtiencv
ToneD«»vTe«: . .DNT DNT
eooo
WUaband Nol*a □
SpMch Noise □
Calibration Rut
ABBREVIATIONS
SISI Tan:
B4k4iy TVPtf —
Tytnp*W)4W«l"—
ME PreuUI'it. ^
Reflex Decay —
ME Reflex —
DNT
DNT
DNT DNT
B -B- '
DNT
DNT
DNT — Did not test
NR or — No re^ionta
SF ~ Sound field
MCL — Moit comfortable
loudneu
UCL — Uncomfortltila
loudnatt .
SHT - $j)««eh ra^tton
tHt^ola '
-COMMENTS -
Type: Bilateral, conductiva
PTA — Pure tone aver.
600-2000 Hi,
PB — Phonaticallv
balanced word
list*
AC — Air Conduction
BC — Bona Conduction
LV - Live Voice
SevarltV! Mild
gig pno|ly Otitia media
Abaent Afaterrt IK Hz
Signatutv of Bxaminer
Figure 8-28. Audiologic findings typical of bilateral otitiB media.
8-77
U.S. Naval Flight Surgeon's Manual
NAVAL AEROSPACE^ n/l|piCAL gEIEf RCH ^BORATORY
MIDIOMETRIC REPORT
NAMI 6120/4 (R*v. B-7S)
NAME .
AGE —
.RANK/GS LVL.
.SSAN.
.SEX.
.FACILITY-
.EXAMINER.
Audk>m«tric
^ It H ^
12B
IHJRW1!@l«li AUDIOGRAM
AUDIOGRAM CODE
.DATE.
0
10
20
1
8
S
i
I
I 90
100
110
260- Bde "''■iooe"*''20(jo
4000 SOOO
Ear
Air
Bona
Un-
Ua«k«d
Milk ad
Un-
Maikad
Matfcad
R
0
A
>
>
Red
L
X
<
SPEECH AUDfOMlTRV
Maiking '
L
W \
n
SF
LV or
Rac.
SRT
45
\^ R
5
Rec
PB
%
100
\. R
100
Rbc
P8
Laval
85
40
MCL
UCL
Matfcing
750 1S0O
PURE TONE MASKING
WMaBand □ Narrow Band □
L R Fraquancv
3000 .flOpO
5pf^N«Sa
-Calibration Raf
ABBREVIATIONS
Tana Dacav Tatt:
SiSi Tail:
DNT
PNT
..-1. t
DNT
DNT
BJk^tv Typa: DNT DNT
Tvrripanogram — A A
ME Prauura Q 0_
Raflax Dacay Nen Nea
ME Raflax — — 122- AfeHEl
1 K m
DNT — Did not tatt
NR or — No ra^ionia
SF - Sound f laid
MCL — Moit comfortabia
ioudnatt
UCL — Uncomfortabla
loud nan
SHT - Spaach raeaptton
tliraihoM
-OOMIMENTS-
Tvpg; Onllatarat^conduettva
PTA
PB
AC
BC
LV
' Pura tone avar.
500-2000 Hz.
' Phenatieally
balancad word
lltti
Air Conduction
Bona Conduction
Lhia Voica
Severity : Mild
DiaBnoilg: Osalcular discontinuity gecondarv to
, ^ haad trauma
SitpMun-of-Eimmfatr
Fiffm 8-29. , 4u4jiplogic findiii^ typical of peeicjiliiir diacQAtiniiity.
8-78
Otorhinolaiyngology^
NAVAL AEROSPACE MEDICAL RESEARCH LABORATORY
ACOUSTICAL SCIENCES DIVISION
AUDIOMETRIC REPORT
NAMI 6120/4 (Rav. 5-7B)
NAME—, —
AGE SEX FACILITY-
.RANK/GS LVL.
.SSAN.
.EXAMINER.
Audlomatric
Wabar
PURE TONE AUDIOGRAM
Fraquancy In Ham
AUOiOGRAM^XJOS
.DATE.
0) 10
IS
m
io
I 30
19
■o 40
c
f
SO
60
78
80
— €
c
>-
-C)
—
<
<
<
c
3-
— E
— c
-
— .
Ear
Air
Bona
Un-
Maikad
Mack ad
Un.
Matkad
Matkad
R
0
A
>
>
Rad
1-
X
a
<
<
SPEECH AUDIOMETRY
Mafkins
*•/
R
SF
LV or
Rac.
SRT
50
\. R
60\
0
Rac
PB
%
84
\. R
98
Rac
PB
Laval
90
40
MCL
UCL
750 1S0O 3000
PURE TONE MASKING
WIda Band □ Narrow Band □
L R Fraquancy
V Toi» Dacav Tait: -CiSfl OHI-
6000
Matking g^^^ ^j,,^ ^
Calibration Raf
ABBREVIATIONS
StSi Tast:
DNT DNT
B4k4tV TVpa: DNT DNT
Tympanogram — B
MEPratiura ■ 2 Si-
DNT DNT
Raf lax Dacav —
ME Raf lax —
ONT - DM not tatt
NR or — No ratponaa
SF - Sound f laid
MCL — Moit comfortabla
loudnatt
UCL - Uncomfortabla
laudnats
SRT — -SpMHh rat^ion
tiiraihold
- COMMENTS -
Tvpa: Unllataral, mixed
PTA — Pura tona aver.
eOO-2000 Hz.
PB - Phonatlcaltv
balancad word
ilm
AC — Air Conduction
BC — Bona Conduction
LV - Ltva Voiea
SgtfarltV! wiHd
Dlaanoati! Chronic P.M., A.S. with sensorineural involvemant
.Atiisoi , 100P.Ha-
Signatun of Examintr
Figuie 8r30. Audiologic findinga typical of chronic otitie media.
8-79
U.S. Naval Fli^t Sui%aDtl*s l^ual
NAVAL AEROSPACE MEDICAL RESEARCH LABOftATORY
ACOUSTICAL SCIENCES DIVISION
AUDIOMETRIC REPORT
NAMI 6120/4 (Rov. 5-75)
NAME.
AGE—
RANK/GSLVL,.
-SEX.
.FACILITY-
.EXAMINER.
Aud lonrvBtrlc
Wabar
- L R ^
PURE TONE AUDIOGRAM
Fraquancy In Hartz
AUDIOGRAM CODE
-DATE.
Ear
Air
Bona
Maikad
Masked
Un-
Ma>kad
Maikad
R
" 1
0
A
>
>
Red
L
X
<
A
Blua
SPIEECK AUDIOMETRY '
Masking
L
R
SF
LV or
Rac.
SRT
50
45
Rec
PB
85
88
Rec
PB
Laval
90
85
Rec
MCL
Madcing
750 1500
PURE TONE MASKING
WIda Band □ Narrow Band □
U R
Tone Dacay Tatt: — Nf 8 ,
3000
Fraquancy
6000
Wideband Noiie □
Speech Nolia B
Calibration a«*
SISI Test:
Bdkiw Type: . IV
TVtniitlfOgram
)il#ran'iir^^ ■
Ratiax'Oaeay
ME Reflex
IV
ABBREVIATIONS
DNT -Did not tan PTA
NR or — No response
SF - Sound field PB
MCL - Most comfortable
loudnan
UCL - Uncomfortable AC
loudness BC
SRT ~ Speech reception LV
threshoM
- COMMENTS -
Tvpa: Bilateral. Sensorineural
- Pure tone aver.
SOO-2000 Hi.
- Phonaticallv
balanced word
Ifita
■ Air iGenduetton
- Bona Conduction
- Ltva Voice
jfit; ..7.
Nag
80
85
Savarity: M«a
Diaflnoals: Ototoxicity (Kanamycift) '
1000 Hz
Signatun of Examiner
Figttire 8-31. Audiologic findingB typical of dnig ototoxicity.
8-80
Otorhinolaiyngology
NAVAL AEROSPACE MEDICAL RESEARCH LABORATORY
ACOUSTICAL SCIENCES fll^yiSION
AUDIOMETRIC REPORT
NAM1 6120M (flav. B-76)
NAME.
AGE —
, RANK/GS LVL.
.SSAN.
.SEX FACILITY-
.EXAMINER.
Aud iomatric
Webar
^ L R ~
WR£ TONt AtJDIOSRAM
Fraquancy in Hartz'
AUDIOGRAM CODE
.DATE.
la
Z
<
CD
e
X
i
?
S
X
0
10
20
30
40
eo
90
too
110
(
t
?^
3
—
\ —
1
Air
Bona
Ear
Un-
Matked
Maskad
Un-
Maskad
Maikad
R
0
A
>
>
Red
L
X
C3
<
I 1
Blua
SPEECH AUDIOMETRY
Matking
R
SF
LV or
Rec.
SRT
45
10
LV
PB
%
38
95
LV
PB
Laval
85
50
MCL
UCL
MatkinB
750 1800
PURf TONE MASKING
3000
6000
Wideband Nolta □
Spmch Noiaa □
Calibration Baf
Wida Band □
Tewa Decay Teat;
SISI Text:
Narrow Band □
L
R
Frequencv
Pn<i
_Neo .
4000 Hr
Pos
Neg
2OO0 Hz
Pos
1000 Hz
Neg
DNT
4000 Hz
B^k^y Type: — -
Tyntpanogram —
M E Praatiira — •
Raif lax Decay —
lulE Reflex —
III
Pos
DNT
Absent 90
IK Hz
IK Hz
4t Hz
DNT
NR or
SP
MCL
UCL
SRT
AieREyiATioNS
PTA
PB
— D id not tan
— No raiponaa
— Sound field
— Most comfortable
loudna*«
— Uncomfortable
loudnait
— Speech reception
thraihold
COMMENTS -
TvPB! Unilatafai. naurai
AC
BC
LV
— Pure tone aver.
500-2000 Hz.
— Phonetically
belencad word
lltti
— Air Conduction
— Bone Conduction
— Live Voice
Ssvarity: Mild
Diagnosis: Acoustic Neuroma A.S.
Signimn of exmnimr
Figure 8-32. Audiologic fintjings typical of acoustic neuroma.
«
8-81
U.S. Naval Flight Surgeon's Manual
NAV^L AEROSPACE MEDICAL RESEARCH LABORATORY
ACOUSflCALl^tiNGES DIVISION
AUDIOMETRIC REroRT
NAMI 6130/4 (R«v. 5^75)
NAME.
AGE_
.RANK/GS LVL.
.SSAN.
-SEX-
. FACILITY.
.EXAMINER.
Audiomatric
Weber
^ L R
t26
PURE TONE AUDIOGRAM
Freciuancy in'Hern
AUDIOGRAM CODE
-DATE.
2&Q
SOO
1000
2000
4000 8000
«A
z
<
a
I
o
f
I
90
100
i —
!
=5
—
—
^
A
^
1.
i
Ear
Air
Bone
Un-
Masked
Masked
Un-
Meakad
Maiked
R
0
A
>
>
Bed
L
X
a
<
<
Blue
SPEECH AUDIOMETRY
Mask ing
L
R
SF
LV or
Rec.
1
SRT
0
Coulc
Rec
Not
PB
%
100
Test
Rec
PB
Lavel
40
MCL
UCL
Matking
~ 780 ' 1S00
PURE TONE MASKING
Wide Band □ Narrow Band n
L R
Tone Decay Test:
SISI Test:
Meg Neg
3000
Frequency
1 000 Hz
6000
Wideband Noise □
Speech Noiae □
Calibration Rof
ABBREVIATIONS
PTA
BdkJsv Tvpe: DNT DNT
Tvmpanogrwn— A A
M E Preisure Q Q
Refle}$.DecBV — PNT PNT
M E Reflex —
DNT — D id not test
NR or — No response
MCL — M0st cOrn'fbrtable
loudness
UCL - Uncomfortable
loudness
SRT — Speech racaption
thratfioKI
- COMMENTS -
Type: Unilateral. Sensorineural
PB -
AC
BC
LV
Pure tone auer.
500-2000 Hz.
Phonatically
balanced word
lists
Air Conduction
Bona Conduction
Live Voice
Severity: Extreme
Diagnosis: Mumps as child
85
Absent
1000 Hz
Signature of Examiner
Figure 8>^33. AudiologiG findings typical of epidemic parotitis.
8-82
Otorhinolaryngology
NAVAL AEROSPACE MEDICAL RESEARCH LABORATORY
ACOUSTICAL SCIENCES DIVISION
AUDIOMETRIC REPORT
NAMI 6120/4 (Bev. 5-75)
AGE —
. RANK/GS LVL..
.SSAN.
_SEX FACILITY.
.EXAMINER.
AudlOfnstric
Wabar
^ L R ^
PURE TONE AUDIOGRAM
Fraquancv In Hertz
AUDIOGRAM CODE
.DATE.
1000
2000
4000 BOOO
Ear
Air
Bona
Un-
Masked
Masked
Un-
Mssked
Masked
R
0
A
>
>
Red
L
X
C3
<
<
Blue
SPEECH AUDIOMETRY
Matktng
R
SF
LV or
Rec.
SRT
20
18
Rec
PB
%
64
72
Rec
PB
Level
60
58
MCL
UCL
Maiking
750 15O0
PURE TONE MASKING
Wide Band □ Narrow Band □
i. ..B
Tbna Decay Ta«t: — Ba*
Jitifi U.9S.
3000
Frequency
2000 Hz
1000 Hz
6000
Wiaetiana Nd&a O
Siieach N^t>a □
Calibration Raf
ABBREVIATIONS
SIS) Tatt:
Neg Nag
tympatroorcm — DNT DI^T
ME Pr9s»ura —
Reflex Decay —
ME Beflax —
ONT -Did not tart
NR or — No raiponie
SF — Sound field
MCL — Most comfortable
loudness
— Uncomfortabia
loud nest
- $p«!ieh ritsapttcip,
WfrciaHoM
- COMMENTS -
Type: Bilateral. Sensorineural
UCL
SRT
PTA — Pure tone aver.
500-2000 Hz.
f B T Plipiiatlcally
' balanced word
lists
AC — Air Conduction
BC — Bone Conduction
LV - Live Voice
Sewei-itv; Bv PTA not sianlf leant but marked due
to low PB scores ;
niaynnsis: Presbycusis
Signature of Examiner
Figure 8-34. Audiologic findings typical of presbycusis.
8-83
U.S. Naval JFlight Surgeon's Manii^
SECTION ni
THE NAVY HEARING CONSERVATION PROGRAM (HCP)
Infroductioii
Acoustieal noise is inextricably entwined with many naval operations ranging from diverse
weapons systems and the propulsion systems of weapons platforms to the industrial aciJvities
which support them. Navy personnel must frequently work in noisy environments. Adequate
noise control has not been incorporated in most systems because of economic factors or because
noise control was not included in the original development or procurement cycles. As a result,
thefe has been m increasing concern' about safety and health aspects of excessive exposure
to k&he in diily dlietatibtis.
The Navy Hearing Conservation Program (HCP) is currently a medically oriented preventive
program administered at the command or activity level. Its purpose is to prevent the loss of
hearing in military and civilian personnel who must work in hazardous noise environments. This
is to be ^co^plishpd by a compreheiisive program which includes noise exposure analyses,
pe«softffl~heaAig proteetion equfanent, momtoring audiometry, education, and noise control
engineering. Tlie HCP had ib bc#tmingp ili flie aviation community, probably due to the
introduction of jet aircraft. It has extended to all parts of the Navy, but there is a considerable
lack of uniformity in procedures, a lack of continuity in coverage, and a different level of effort
among the various sectors of the Navy.
In the pM|„|r.3ft;ji more or less accepted tiiat a hearing loss accompanied certain jobs, and
many new erfpoy^s were told "you get used to it." Such labels as "aviator's notch" or
"boilermaker's ear" were accepted as part of tradition. During the 1960's, however, changes in
attitudes and values occurred, and in 1970, Congress passed the Occupational Safety and Health
Act (OSHAct) which required employers to provide a safe and healthy working environment.
Exeewtive Order 11807 extended the OSHAct to all branches of the federal government
including the Navy, which, as a major employer, is expected to develop and implement
programs to prevent any employee hearing loss arising from noise exposure.
In many Navy and Marine Corps facilities, hearing conservation is being accomplished.
Audiograms show very little loss of hearing because hearing protection is being worn on and off
the job, noise abatement and control are progressing as money becomes available, and education
is bringing about an awai«iies8.of l|ie problem of noise and its effect on hearing.
8-84
Otorhinolaryngology
Why, then, the variability in the effectiveness of programs? The answer, though not simple,
seems to he with the perception of prioriljes an^l the toiits of resources. It has to do with
people, hoth t}ie proteetors md the pw^tected. WmMe programs to be suGcesrfnl,,4Wi«W;|^
ea<^ Boiiail^d must spend at least 50 pe*qeat Ws time coordinating the flow of people for
hearing m% procurement of ear protectors, the training of technicians, the paperwork
requesting surveys, the reporting of results, etc. With this in mind, this chapter will discuss ways
to implement a successful hearing conservation program.
]|iiplenienticH$|iO ,pi
Navy policy, as stated in SECNAVINST 5100.10C, emphasizes that accideHt pfev«nJ4^^,
safety, and occupational health we inherent responsibilities of individual commands. Workplace
mm control and hearing conservation programs are important aspects of this overall
responsibility. In a message from SECNAV dated 10 December 1976, all commanders are
directed to thoroughly survey their commands for noise hazardous areas and to implement
hearing conservation programs which meet the following basie elemfntS! ■
1 . Continuing command attention to prevent ititilse-illdiiced heartag Mss
2. Initiating coirrecfive actibri to redttltj^s ft#se at its source
3. Identifying to parent commander those significant noise hazard problem areas which are
beyond their capability to correct or control
4. Implementing and enforcing effective hearing protection programs in accordance with
BUMEDINST 6260.6B until noise levels have been reduced to non-hazardous levels
5. Continuing programs for education and indoctrination regarding the hazards of noise in
order to gain wflling personnel participation
6. Command emphasis on superviflory enforcement of wearing, protective equipment
mcluding initiation of disciplinary measures where necessary.
At shore activities, medical support of hearing conservation program elements is provided by
tiie F^fin^ occupational and preventive medicine services. Industrial hygiene, safety, and
industrial medical services are now available in most regions. For ships underway, the medical
department is relatively self-sufficient, except where specific services are supplied by the
Environmental and Preventive Medicine Units. When ships are docked, services are generally
supplied by the r^on aitd, more directiy, by the nearby naval station brandi clinics whi«h are
oriented toward fleet support
OPNAVINST 5100.80 tasks the Bureau of Medicine to provide technical and professional
occupational health assistance and guidance to assist commanding officers in meeting tireir
8-85
U.S. Naval Flight Surgeon's Manual
responsibilities in this area. BUMEDINST 6260.6B states that "Where a noise hazard exists, a
hearing conservation program, using the basic elements contained in enclosure (1) as a guide,
sh^ fife' f^YlA^i^^ ly" Ihe meMcd' d^R(^r,' conjunction with the department heads
cd66€tlied, for the approval of tiie coirnihaii^^ officer." Thus, tfie medical officer or Tiis
designate is responsible for the preparation of th« Bfeal command instrUCttbltfor any command
or activity within his jurisdiction. A model instruction is mduded in Appendix 8-B for liie as a
guide. !
The newly-appointed hearing conserviEition officer should assess his resources and the
shortages in his command. He should, as a first approximation, estimate the number of
personnel exposed to hazardous noise j Mt everyone is ^posed. He ^ould work closely with
the medical officer to obtain required services such as hearing tests, ear protection, referral
guidelines, and educational materials. He should work with safety specialists to help identify
problem areas and to monitor compliance in the wearing of ear protection. He should work with
4m regional industrial hygienist (or EPMU hygienist) to plan, coordinate, and help perform
noise surveys to identify nttise hazardous areas and ecpiipment, and tQ identify all noise exposed
personnel. He should work with supervisors , to coor^ate all dements of .hestri|^,Cp|is#vatioii
at that level. He should represent the interests of hearing conservation at |!ie poi»mand/staff
levd. "
the medical officer should work with the hearing conservation officer to help coordinate all
medical aspects of hearing conservation. He should coordinate tiieiee services witii the regional
occupational healtii sendee and flie regional ENT service. He should fmm '&md aidequately
trained personnel are on board to provide services and that adequate audiometric facilities are
available. He should evaluate all audiograms and refer patients with problems to the ENT service
for further evaluation.
One of many problems noted in surveys done hjr WAMf Wdl % i9le Ki^^
Health Center (NEHC) is that a program at a particular command is achieving its goals and then
the one person who worked hard to promote the program is transferred. The program collapses
until someone else appears several years later and begins again. Every effort should be made to
provide continuity of the program and its elements in spite of the transfer of personnel.
Another problem noted is tiie use of untrained corpsmen to perform hearing tests, while within
the region tiiere ate trained technicians being utilized for other duties. It would be wise to
encourage a team concept and to hold regular meetings with the whole group induding
audiometric technicians, nurses, doctors, industrial hygienists, and safety spedsHstS. AH team
members including the medical officer should attend, at least annually, a workshop on
occupational hearing conservation such as those conducted by NEHC.
8-^
Otoihinolaryngology
Finally, it must be emphasized at all levels of the medical establishment that there is no cure
for noise-induced hearing loss, only prevention. No one is going to report automatically to the
clinic and presen^'Mwsei'Hs a >«!ft(l^tfe for k program of heartflg loflS privention. The HdP
must provide people to go out into the workplace to identify noise-exposed personnel and t»
arrange for the conservation of flieir priceless sense of hearing.
Noise Measurement and Exposure AnalyfP .^j,, . , .„
,: trhe first step in the i4entif icK^on of noise hazardoi*9tpre«8 HWH-exposed personnel is
the noise survey. The !ly,pe8 of surveys and the different -mpesoi ffll?>e)?i^c^ R swrvey are
discussed below.
The preliminary survey is any type of cursory or gross evduation of possible noise hazards
that any member of the hearing conservation team notices during a casual walk-tiwough of a
work area. This could also take the form of a response to'a eall from a supervisor who has heard
compMtit»' of a noisy piece of equipment or a noisy process. The rule-of -thumb criterion for
this subjective appraisal is that a noise hazard may exist when it becomes necessary to shout at a
distance of three feet in order to communicate. ' ' ' .' . "-t
Any of the jiteve^tnm«teneel5te1ftis may lead to a feqi^fef ife ifidustrial hy^enist wmMm
in and make a meastifettieiit with a sound levfel TnetWr'1%^>#iehist should make sufficient
measurements to determine, first, if the suspected area is potentially noise hazardous and, next,
how many people are exposed and for how long, A complete documentation of the
measurements is required for any future inspections. ,
A routine noise survey and noise exposure analyEas, Conducted at least every two years
(every six months at NAVAIR field activities), should entail a thorough analysis of all noise
hazardous areas, equipment, and processes. It should also list the names, rates, and
identification numbers of all exposed personnel and a reasonable estimate of their daily dose or
time-weighted exposure level. If the noise varies considerably for certain individuals during^lg^
workday, noise dosimeter measurements may be necessary in Bfieif' fo dbifuaiife^'ii<»'
expoSuye,'*flie hygienit aMH iJib tlole piteHrious atteinpts at noise control, the use of ear
pt'dfeetidh (or lack of ear protection), and the posting of signs and decals in noise hazardous
arese artH on equipment. ,
An engineering noise analysis including octave^aWtf' Or' l/t*^ta^-bmd ^e£^m andyA
is perfofflled' When It becomes necessary to piitpoint noise sources for noise <rdntrol
engineering. It is important to document everytiiing so that when noise abatement has \mm
performed, a post hoc measurement will show the improvement due to the noise control.
8-87
U.S. Naval Flight Surgeon's Manual
, In addition to the need to identify noise-exposed personnel, a noise survey is required in
o^der to comply with the OSHAct. The specific requirement is a documentation of the
Arwd^ted. levels and a listing of noise-expcised personwel where not8@> a^ $0 dBA^K
Noise survey information is also necessary when a worker files a claim for compensation for
hearing loss due to prolonged exposure to noise. The adjudication by the Office of Workers
Compensation ProgramB (OWCP) requires' a " co%We "noise ^tposure history including
exposures at 85 dBA attd Mfeve f or 1*(e Mffe p^^^ individual by the
U.S. Government. For miUtary personnel, a noise expoaire history shottid bts avdflable in every
health record in order to verify that the hearing loss was due to occupational noite exposure '
rather than to some other factor.
Audiometry in the HCP
After the noise survey has been conducted and lists of noise-exposed personnel have been
drawn up, the other elements of the HCP are set in motion. Audiometry is one of these
d^iftents. Because an audiometric test is essentially a clinical test, it must be conducted by
mddfeal personnel with professional oversight. WhUe audiometry seems, on the surface, to be a
Ftlativfely simple f rocedujsfe i| «ftiiEbfeeeomfis a burden to the elinie because of tfie n^y
*^^J^^rti^i!HiEPIStt#;»n4!ia||''to-day human decisions which njust lie made.
The Physical Requirements for Audiometry
In order to conduct audiometry, the following are considered basic and essential:
1. A trained and qualified technician
2. A calibrated audiometer
3. A certified audiometric chamber. . t .
jlteijumiimpoitailt of the^iequirements is the trained technician. The testing of hearing is
a task that requires not only the knowledge of a, technique^. but afeo ^^^Pn awitfeness of the
technician-subject interactions. The subject is asked to judge whether (gr jaot he hears a faint
sound and then give a response. The technician must weigh each response in relation to the
threshold technique and sometimes in the context of "game theory." Thus, the technician must
be trained for this purpose and be certified on a one-to-one basis by qualified instructors. Such
trdning is conducted by the Hearing Conservation Semm qf MMlSl. While over 250 technicians
are trained each year, as many as half of those trained are not utilized by clinics for testing
hearing.
8-88
Otoiliinolaryngology
The next requirement is for a calibrated audiometer. The calibration really consists of two
elements - the daily biological calibration check and the "annual" physical calibration. Bolh
are recjuired by BUMEDINST 6260.6B and the proposed guidelines in the Woiiff (5^jatrolv|fc^.
The biological calibration is considered to be more important because the tecJiniciatt is tr^ed
to compare his (or another carefully chosen person's) hearing with his previous base line
audiogram on each audiometer. If his hearing is 5 dB or less different relative to the base line,
the audiometer is in calibration. If this procedure is not done daily, audiograms performed for
as long as a year may be inaccurate. NaturaUy, a daily entry in a continuing log is a necessary
requirement to document the biological cahbration dteck/ Alliitffl 'pfi^sififd %rfibf M©Sl
preventive maintenance is perform^ by the l^mdioWetit* K^M^^^^
NAMI. This service ji^it^ ,to,#ac|iyitib mdi8 cov^^y: BUMEDmST 670 The trained
techniciMi also tau^t minor maintenance of audiometers so that many small daily problems
are taken care of by him or in consultation with the NAMI service consultants.
The audiometric chamber or "booth" must be certified biannuaUy by an industrid hygienist
or preventive medicine technician who is quaUfied.to o|)#at^ t!te aiStavi-bMamiii analyzer at
to# f^<ia pressure l©*elf. fi^ Wi}ui»fe4 levels' ^ BUMEDINST 6260.6B. If the booth
mmu 'fe reijuired levels, the data are posted on the booth and signed by the hygienist. If it
fails, maintenance and/or relocation may be necessary.
Most booths aboard ships do not meet the requirement of BUMEDINST 6260.6B. As an
interim measure, NAMI installs a set of "Aural-Domes^' ©n ^.pa^honp of those ;^ometer8.
Audiometer Types
There are two basic types of audiometers used in the HGP, the manual and the self-recording
types. The manual audiometer is preferred since the technician is in. control of file test «nd
threshold levels are obtained directly. The Bel{irecorJi^,,S|||#ometer lip only on^
can be set up as a gEc#|> m^i^wptef to monitor several people, at
a time. Considering the large numbers of people who need annual monitoring audiograms, the
group fttdiometer seems to be the only solution to the problem. When one looks carefully at the
audiogram tracings, however, a pattern of operation emerges that seriously questions the utility
of group testing. AU too often, the technician, overwhehned by the quantity of audiograms and
paperwork generated by such large numbers of tests, tends to ignore the moltbi^e reqpsefl^#
of monitoring the progress of the test. The result is that most audiograms in health records are
invalid for technical reasons. .. .<j- <
B-89
U.S. Naval Flight Surgeon's Manual
Requirements for "Valid" Audiometry
BuMed sent a message to all medical activities in August 1976 raisii^ aerioils questions
about the quality of audiometry in the HCP. The main points were: '
' 1; Audiometry must be performed by trained technicians.
2. A regional pool of audiometers should be estabhshed.
I, A new set of criteria must be applied to each audiogram. .
i
The set of criteria is as follows:
1. It must be possible to draw a horizontal line through tfie centerpoints of the tracing.
f2 liiere ikmt be at least eight center line crossings at feach t&t frequency .
3. A 10 dB validity check must be done at 3 kHz in each ear.
AdiKtianal checks should be done if tracings of less tiian 5 dB peak to peak are observed.
Failure to mmt my one of these criteria makes an audiogram "invalid." In additioji, the
BuMed Message Hmits the number of persons to be tested by group apdiometry to no mojEft Jhan
four persons at one time. Pending the outcome of a study of group audiometry by NAMI, this
restriction should be applied.
Audiometry Performed for the HCP
' basic audiometry performed for Ibe HCP is air conduction testing at six frequencies
(500, 1000, 2000, 3000, 4000, and 6000 Hz). This audiometry is conducted for the purpose
of establishing a base hne or "reference" audiogram which is permanently attached in the health
record and against which future audiograms are evaluated. The other purpose for audiometry in
the HCP is for annual monitoring of hearing.
BMch |ieKities and physicd examination sections conduct physicals, and the audiogram is a
pM ictf 'ifaaiif j^hysicals. The same heariiig test may be^iiauMfel'fer bolh the HCP and the
physical. The interpr^*€bn, htJtWevejr, is quite dte^tSnt f tit eaeb. In the HCP, the difference be-
tween the current monitoring audiogram and the reference audiogram is examined for evi-
dence of "shift" of threshold. In the case of the physical examination, a "pass" or "fail"
determination is made with respect to a set of numbers in the Manual of the Medical Depart-
ment, dfe^ter 15. Thik Mtuation hj^ been overlooked in the past, to the detriment of the HCP.
The base line audiograms obtained upon entry into the service are rarely valid for use in the
HCP. A base line test should be conducted as Soon as a person starts into a rate which will lead
to a noise-prone job.
8-90
Otorhinolaryngology
Hearing Protectors
The main purpose of hearing protectors is to reduce the noise entering the ear. Ideally, the
protector should reduce noise to a level below 90 dBA so that an individual may be able to
work a regular eight-hour day. There are some situations wtere fltfe is not possible, so a time
exposure analysis must also be made. Most individuals, however, can be protected by either
plugs or muffs or a combination of both.
Basically, a hearing protector attenuates or reduces the amount of noise reaching the
ear by vh-tue of placing a combination of materials in or around the ear. In order to be
effective, it must make good contact with the ear and produce an airtight seal. It must
also be relatively flexible and nontoxic. Finally, it must be as comfortable as possible so
that it will be wotn.
Hearing protectors selected by NAMI lot um by the Ifavy are evaluated not only on their
attenuation characteristics, but also upon theh comfcit, ease of use, lack of toxicity, and their
cost. Current approved protectors (Table 8-12) cover a wide range of types and apphcations.
The basic or single flange ear plug, V-51-R, comes in five sizes. Each ear must be^ fitted
accurately by a trained corpsman. The triple flange plug, m three sizes, is used by people who
cannot get a good fit from the V^51-R. Both of these types are b^t ^8#>y workers in noisy
environments where theise is i»o need to mmove or replace th^m more than two or three times
daily.
A long-term soft plug, the EAR, is a special, closed-cell foam. This is used as a
semidisposable plug for long flights in C-130's or C-141's. The Silaflex is a silicone putty which
is very comfortable, cheap, and effective. It, too, is good for long flights.
The SoxWd-Batt, a headband-mounted ear cap, is good for short-term, eagy.ts>-place usage. It
is vmi by supervisors or others who transit noisy spaces frequently and need a good, temporary
ear plug.
The large, "mickey mouse" ear muffs are standard on the flight Une and flight deck. They
are high performance muffs which can be mounted on the flight deckhehnet systein. These are
the only muffs adequate for protection sdsoard the flight deck during normalSair operations.
They would, however, overprotect people who work ui moderate levels (90 to 105 dB) of noise
and would also, probidily be uncomfortable. Since they have a rather stiff spring headband, they
are not very good for industrial situations. Type 1 and Type H muffs are recommended for those
situations.
8-91
Table 8 -12
Hearii^ ftotective Devices
Manufacturers
Nomenclature
Ear pefefieter V)^51R
Comfit, Triple Flange
SilaflexiBffeterPs^)
E A R or Decidamp
Sound-Ban
Strai{|htaw«v Muffs
("Mickey Mouse"
ear muff) -
Ear Plug Cases
Carscope Earplug Gauge
Open to Lowest
Bidder
Op^ to Lowest
Bidder
Tyj» of Protecttr
tnsert Earplug (sized)
Insert Earplug (sized)
Non-Har^ning Sitieone
Foam Plastic Insert
Headband, Earcaps.
Circumaurai Muffs
For 9AN/2
For 9AN/2
Type I Overhead
Headband,
Cirmimaural MUff '
Type II Napebahd
Circumaural Muff
for use with Hard Hat
Federal Nornenclature
Plug, Ear, Noise Protection
24's (X-Small) (White)
24's (Small) (Green)
24's (Mediam) (int. Orange)
24's (Large) (Blue)
24's (X-Large) (Red)
Plug, Ear, Noise Protection
24's (Smatt) (Green)
24's (Medium) (Int. Orange)
24's (Large) (Blue)
Plug, Ear, Hearing Protection
Cylindrical, Disposable 200's
Plug, Ear, Hearing Protection
Unhrersaft Size, YellowJOOPair
Plug, Ear, Hearing Protection
Universal Size
Aural Protector, Sound
372-9AN/2
Replacement Filler, Dome
Replacement Seal, Dome
Case, Earplug 1 2's
Gause, Earplug
Aural Protector, Sound
NSN
Aural Protestor, Sound
6515-00-442-4765
6515-00-467-0085
6511'4)p467-CI089
651&<)0-442-#O7
6515-00442-4813
6515-00-442-^21
6515-00-442-4818
6515-00-467-0092
6515-00-133-5416
6515-00^137-^5
6515-00-392-0726
4240-00-759-3290
4240-00-674-5379
4240-00-979-4040
6515-00-299-8287
3 (6515-00-117-8552
4240^)0-691-5617
4240-0&022-2946
Colt
.81 pk
.84 pk
.86 pk
.86 pk
1.15 pk
3.03 pk
2.84 pk
2.48 pk
7.73 pk
17,78
200 pr
3.15 ea,
5.65 ea.
.27 ea.
1.06 pr
.20 ea
1 .92 pr.
2.i0ea.
4.42 ea.
CI
cn
f
o
B
o
Otorldnolaryngology
Muffs are safety items, hence, they cany the 4240-series stock designation. Plugs are
medical items; they have the BBlS^igmed designation. Note iawlM#B» fe «W
number for the NSN system* Older stock numbtersrcont^iiing only 11 digits will be rejected by
the supply system computers.
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American Standards Association. Specifications for audiometers (ASA Z24.5-1951). New Yorit: Ainerican
Standards Association, 1951. .o-'v ' ^-nu i .i > r. ; ' ^^f?
Cawthome, T.A., & Hewlett, A.B. Meniere disease, JVoce^fnf* 19/ tfe'^bytrfStfcfety^ 1954, 4ftl
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Da*iS, H„ & Silverman, S R. Hearing and deafness (3rd ed.). New York: Rinehart and Winston, Inc., 1970.
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U.S. Naval Eli^t Surgeon's Manual
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O'Neill, J J., & Oyer, H.J. Applied audiometry. New York: Dodd, Mead and Co., 1966,
Rose, D.E. (Ed.). Audiological assessment. Englewood Uiffe, New Jersey : Prentice Hall, Inc., 1971.
Sataloff, J. Hewing loss. Philadelphia and Toronto: J.B. Lippincott Co., 1966.
Saundas, W.H., & Garner, RM.fhamMotherapy in otolaryngology. St. Louis: C.V. Mosby Co., 1976.
as. Naval F^htti^f'ImmMl'Mfi^d by BioTechnology, bic, under Contract Nonr46l3(00). Chief of
Waval Operations and Bureau of Metfcine Se^eiy. Washington, D.C., 1968.
'r. ' , , ■ N
8-94
Otorhinolaryngology
APPENDIX 8-A
MINIMAL EQUIPMENT FOR E.N.T. EXAMINATION AND TREATMENT UNITS
nil luui 1 L
Itam
Federal
Stocl< Number
1
Light, Floor
6530-706-5100
1
PharyngMt Alrvifay .
6515-300-2900
1
Metal Tongu« [^pi^liF
6516-3^4-5205
2 Boxes
Wooden Tongufl Depressors.
6515-324-5500
1
Laryngosobpe
6515-346-0480
1
Headband, Mirror ^
6515-341-5200
1
Mirror, Headband
6515-347-5200
Laryngeal Mirrors
2
Size 00
6515-347-8400
4
Size 1
6515-347-8500
2
Size 3
6515-347-8600
6
Size 5
6515-347-8700
1
Nasal Snare
6515-367-4700
1 Spool
Wire
6515-367-4780
2
Kelly Curved Forceps
6515-334-3800
2Pkg
4x4
6^10-203-8448
4
Nasal Applicators, Tumbull
6515-303-3600
6
Frazier Suction Tips SFr (Nose)
6g1 5.386-6800
1
Sayer Elevator (Straight)
^15-327-8400
4
Bayonet Forceps
6515-333-6600
1
Knight Nasal Forceps
6515-336-3300
6
Nasal Speculum (Vienna)
6515-369-9100
1
Atomizer Set, Medicinal
651 5-307-0600
1
Vaporizer, Medicinal (Politzer),
6530-794-5520
2
Dental Syringes
6515-985-7106
1 Box
Dental Needles 27 GA Long 1 3/8 In.
6515-181-7412
1
Alcohol Burner
6640-537-5010
2
Intubation Tubes
6515-961-5519
1 Can
2% Xylocaine with Epinephrine
6505-576-8842
Carpules
2 Boxes
Vaseline Selvage Gauze
6510-543-7145
1 Pkg
Cotton Tip Applicators, Q Tips '
6515-303-8250
1
Ear Inflating Bag, PoliUer
6515-306-5400
2
Hartman Forceps (Ear)
6515-333-5400
1
Tuning Forlc Set
6515-338-9200
1
Toynbee Tubing
6515-385-5100
1
Ear Speculum Set, Gruber
6515-369-1600
1
Otoscope
16515-550-7200
8-95
U.S. Naval Flight Surgeon's Manual
APPENDIX 8-A (Continued)
MINIMAL EQUIPMENT FOR E.N.T. EXAMINATION AND TREATMENT UNITS
The foUowing instruments may be obtained from Stqrz Instrument Compsny.
Catatog Number
NS60
N6300
N382
N410
N460
mm
N^610
Item
Ear Basin, Goldnamer
Pneumatic Otoscope Set
Applicator, Turnbull 5 in,
Billeau Loop (Smalt & Medium)
Hook 8i Spoon, Ear, Gro»
Forceps, Ear, Noyes, Extrig Fine
Serrated Jaws
Suction Tube, Baron 5FR with
Air Cutoff Valve
Amount
1
1
1 dz
2
1
1
Prfee
$2.50
$56.00
$13.75 per dz.
$ 3,50
$ 6.75
$27.00
$ 4.25 Ea.
■TtlfrMtewing instruments may be obtained from V. IVluller Instrument Company
(Prices as of 1 974)
The following equipment may be obtained from tfie iSmpafiy ifidlcafad.
Cii^tdliliimber
Item
Amount
Price
AU'5593
RH-5045
Buck Ear Currette, Blunt
Devilbiss Syringe, ? oz. {For Unjxtig0f0\
2
1
$ 2.50
$14.00
Amount
Price
Monoject "220" Sterile Disposable Splint Needle, 18 GaU0e3i5 In,
Diamond Point 1 0Q/cs - v ' '
Sherwood Medical Industries Inc. - ...t.
183.1 Olive Street
St. Louis, Missouri 63103
Gelfoanr. Absorbable Sponge
The Upjohn Company
^Kialamazoo, Michigan 49001
Surgical Suction and Pressure Apparatus
6515-312-8200
Examination Chair
845
850
Federal Stock Number
6530-319-0550
6530-704-6010
$41.00
$ 0.84
$450.00
$900.00
$150.00
(Prices as of 1976)
8-96
Otorhinolaryngology
APPENDIX 8-B
MODEL INSTRUCTION FOR ESTABUSHING A NOISE CONTROL
AND HEARING CONSERVATION PROGRAM
The following model instruction, based on one prepared by Commander, Training Air Wing
Six, NAS Pensacola, describes the steps in estabUshing an effective ' HCP programrThte
instruction should be modified to meet tiie specific needs of individual commands.
(COMMAND) INSTRUCTION .....
Subj : Noise Control and Hearing Conservation Program
Ref: (a) SECNAVINST 5100.10C (NOTAL)
(b) OPNAVINST 5100.14
(c) BUMEDINST 6260.6B
(d) NAVAEROSPREGMEDCENINST 6260.1
1. Purpose. To establish procedures for the implementation of an effective noise control
and hearing conservation program. The basic objectives are to control noise emissions where
technically feasible and to prevent hearing loss in personnel exposed to potentia%, feszardous
noi^e sources.
2. Scope. This instruction agpUes to all activities within (Activity) having designated noise
hazardous areas and equipment
3. Background. The policy of the Secretary of the Navy, stated in refefences (a) and (b)
emphasizes that accident prevention, safety, and occupational health are inherent responsi-
bilities of eoininand. Work place noise control and hearing conservation programs are important
aspects of this overall responsibiUty. Where noise control is not economically feasible, a
medically-oriented hearing conservation program, outUned in references (c) and(d) becomes
necessary as a feasible interim solution.
4. Responsibility.
a. Commanding Officers of (Activity) are rcsponsijle keeping abreast of aU ncise
hazardous areas and equipraMt' te#'fehatt institute noise cotltrol measures where feasible,
Additionidly, they shaU ensure that all noise hij^ffidous areas and equipment are labeled witii
NAVMED 626fi/2|^ii!prdous Noise Warning Decitf, and NAYMED 6260/iA, Hazardous N^^
Labels (displayed on hand tools), as appropriate.
8-97
U.S. Naval Eli^t Surgeon's Manual
h. As directed by reference (c), Industrial Hygiene personnel in coordination with
Safety Department personnel are requested to perform the necessary noise surveys to identify
both iJie noise hazardous areas and equipment and also all noise-exposed personnel.
c. The Aerospace Physiologist assigned as Aeromedical Safety Operations Team Member
(AMSO) in conjunction with the Flight Surgeon shall be responsible for coordinating and
ma^toriBg the hearing conservation program. He Aall also provide educational and training
services as required.
d. The Safety Officer and the AMSO team member shall be responsible for conducting
inspections of all activities for compUance with this instraction during administrative personnel
inspections.
e. The Fli^t Suigeon or Medical Officer shall evaluate all hemng loss cases in personnel
detected by monitoring audiometry as required in reference (c).
f. All supervisors shall be responsible for monitoring the usage of hearing protection by
their noise-exposed personnel and help coordinate the periodic hearing testing as required in
reference (c). They shall set an example in the wearing of ear protection and initiate disciplinary
measures for failure to comply with this instiuetion.
5. Action.
a. The use of approved hearing protection (ear plugs, ear caps, or muffs) in designated
noise hazardous areas shall be mandatory during periods of excessive noise. Double protection
(plugs and muffs) will be required during high power turn-ups exceeding five minutes.
b. All personnel assigned to duties within or around designated noise hazardous areas
and equipment shaU:
(1) have a base line or reference audiogram in their health record
(2) have a monitoring audiogram within three months after assignment
(3) have an annual monitoring audiogram thereafter unless the Fhght Surgeon
determines tiiat a shorter interval is required
(4) be fitted with a set of approved ear plugs by trained medical personnel.
c. Approved ear muffs will be used around all operating aircraft. Flight and transient
personnel m^ utilfee approved ear c^s during preflight inspections;or short duration exposures
(less than 15 minutes). Ear muffs and ear caps shall be furnished by individual commands.
d. ftetSoimel who teftise periodic hearing testing or refuse to utilize hearing protection
while in designated noise hazardous areas will be subject to appWpilate discfplinary action.
8-98
Otorhinolaryngology
e. All personnel shall be educated in the hazards of exposure to noise on at least a
semiannual basis.
f. Recommendations by the Flight Surgeon or other qualified medical officer for the
removal of individuals from further noise exposure shall be given command attention.
g. Activities shall submit semiannually a Hst of all personnel assigned to designated noise
hazardous areas to the AMSO team member with a copy to the Branch Clinic. The AMSO team
member shall help coordinate the workload and timely testing of all noise-exposed personnel.
h. Activities shall maintain records on personnel who work in noise hazardous areas,
showing date of most recent monitoring audiogram.
8-99
o
c
c
CHAPTER 9
OPHTHALMOLOGY
Introductign
General Ophthalmology
Refraction and Lenses
Trauma and Ophthalmologic Emergencies
Sudden Disturbances of Visual Acuity
GlaMci^a'
Annual Phyliesl EiffiflftiiiatJdiis on Fli^t Personnel
Eyewear for Navy Personnel
Contact Lenses
Perceptual Disorders
Topics of Interest for Safety Lectures
Bibliography
^ ' btrodueti(Mi
The purpose of this chapter is to convey useful information about ophthalmological
problems pertaining to the airman. References do not answer the questions, "Is he safe to fly?"
or "When can he fly?" The answers to these questions are best determined from practical
experience and from knowledge common to the Flight Sui^eon and ophthalmologist.
The FUght Surgeon is encouraged to obtain consultation and advice from ophthalmologists
and optometrists when it is indicated. However, it has been observed that the Flight Surgeon
can tsdte care of most proM^flnt pelatgd to ey and vfeual parameters as applied to the fli^t
safety of the airman.
General Ophthalmology
The following areas are recommended for an orderly and complete examination by the
FUght Surgeon: i ^
1. Lids and adnexa (Lacrimal apparatus and caruncle)
2. Conjunctiva and cornea
a: Stlfera
4. Pupil and its reactions
9-1
U.S. Naval Fli^t Surgeon's Manual
o
5. Slit lamp exam of anterior chamber (if available)
6. Funduscopic exam
7. Extraocular motility
8. Visual fields
9. Intraocular tension when indicated.
A brief discussion of abnormalities that the Flight Sui^eon will see, and the recommended
management, follow.
Lids and Adnexa
Styes and chalazions are the most frequent causes of complainte. Treatment should consist
of grounding, hot wet compresses, and instillation of a topical broad spectrum antibiotic such as
neosporin drops. Most styes will drain or absorb with this treatment in 5 to ^.Q 4ays.
Chalazions should be treated the same way. If tiley persist for 4 to 6 weeks they usually will
need to be indsed and drained. Also they sometinies cause decreased visual acuity by pressing
on the globe and causing astigmatism.
Epiphora indicates excessive tear production or a blockage of the nasolacrimal drainage
system. Usually epiphora is due to a temporary blockage either caused by a nasal allergy or
secondary to a dacryocystitis. Appropriate treatment should be rendered and the epiphora will
subside.
Conjunctiva
Infections of the conjunctiva are common, and usually are self-limited diseases lasting 10 to
14 days. Recommended treatment is personal hygiene, warm compresses, and frequent (q 3 to
4 hours) instillation of a broad spectrum antibiotic. Do not use steroids unless indicated.
Ground the pilot to avoid spread of the disefise'Via oxygen mask, visors, glasses, etc.
Pinguecula and pterygiums can be treated with topical decongestants for minor inflamma-
tions. They should be referred to an ophthalmologist when indicated. Surgical removal of a
pterygium usually means 'grounding' for at least four weeks. The squadron should be in a
position to allow for this grounding before the surgery is performed.
Sclera
Diseases of the sclera are usually mildly inflammatory and best treated with topical
steroid/antibiotic drops.
9-2
Ophthalmology
r)
Pupil
Acquired disorders of the pupil result in the involved pupil being larger or smaller than
normal. Larger pupils may result from contamination with atropine-like drops. This is fairly
common in medical department petsoimel who work around these drugs. Other causes are
Adie's spastic pupil and hejld trauma. Optic neuritis can also cause a unilateral enlarged pupil
with diminution of direct li]^ mf^m-in^'Wii as Gufiji p^p^, .T^^;^8,shQul4Jll^#ated
tJlPrOUgWy. ' ... J »: >
Causes of smaller pupils are drug usage (narcotics) and contamination with miotics such as
pilocarpine. Homer's syndirome also causes miosis on the involved side.
SUt ^ittpExam(if.availfb^e) , . ' f.im-»i'»b
Iritis is best «iiagnosed by using a slit lamp to see cells and flare in the anterior chamber.
Treatment is to dilate the pupil with long-acting cycloplegics such as horn atropine or atropine to
prevent posterior synechia and the topical administration of a steroid to minimize the
inflammation. Iritis typically last 3 to 4 weeks. The flyer should be grounded during this time.
An ophthalmologieal consultation should be obtained. Recurrent uveitis causes so much 'down'
time with an aviator that separation fi6m flyi%is someimes recommended.
' ^ Funduscopic Exam
Fundus diseases of the young healthy aviator are uncommon and wiU usually fall either into
a group of disorders known as 'central serous retinopathies' or posterior chorioretinitis. In tfie
former, diagnosis can be made by careful exam with an ophtiiahnoscope, notin^ii'l^'bf Hfe
iQf^^^flex and pdemg Qf,,1^^,macula. There wiU be^,4(*P ?D3^«!^r|^ «tecre»8e^f#i!3^fpuity
^ iRidiWaL% The ptesences pf !r|et^ofphop4a Ip a >f|4i^|q diagnostic aid. Treatment
l^jald consist of rest, removal from stressful situations as much as possible, and stopping the
use of tobacco and ingestion of caffeine, as vasoconstrictors are to be avoided. Systemic steroids
are usually not indicated because they have not proven to be effective. Visual acuity usually
returns to 20/20 within 4 to 6 weeks. Posterior chorioretinitis can be ree<^niZed by vitreous
debris and the ptesence of a ftesh chorioretinal lei^M. 'Most 'fcises wiU be dUe to either
toxoplasmosis or histoplasmosis. Management by an ophthalmologisf il tecbmriiended. After
heahng, if the macula is not involved, flying can be resufli^. ,) .j<.;;t '4/ bn« -ioli*!
Extraocular Motility
Once the phorias have been measured, the Fhght Surgeon may further evaluate the
e»tEa«Ealar miiscles by using the;simpte red len&tesfe 'Wftfe a^ed lfenioiivifeairfvofiflfo ej^i-tfld
fixating a muscle hght with both eyesv tite nosmal pii#infc.wiU i8©#j^^
indicates loss of fusion. The tight should be moved into the cardinal positions of gaze. Finding
9-3
U.S. Naval FU^t Surgeon's Manual
the field of gaze with greatest separation of images aids in diagnosing the paretic muscle. A
patch over one eye wilt temporarily alleviate diplopia, but an ophthalmology or other
appropriate evaluation is recommended.
' ^ #«0'|fi^orltl6d ^i^ontafion visual field is all that the FH^t Su^eon need perform. If it
is abnormal, then further testing by tangent screen and/or perimeter is indicated. The FBght
Surgeon who doesn't know how to perform a confrontation visual field must ask someone who
does.
Intraoedar Tcmnon
The dietenttination of the intraocular pressure by Schi<atss tonometer is recoteiraended
annually for all individuals 40 j^bittf of ^e and over. Thq intraocular pregshre should also be
determined whenever cUnicaUy indicated sueh «s throif^ findings of an enlarged optic eup or
history of an elevated intraocular pressure on previous occasions.
Refraction and Lenses
The Fhght Surgeon will be called on to evaluate refractive errors, especially in Naval Flight
Officers (NFO's), and in older aviators. He can, if he chooses, refer these personnel to an
optometrist for the appropriate refraction. However, it is still the Fhght Surgeon's responsibility
to ilisure that corrective lensps are prescribed and that they are appropriate for the specified
service, group.
Rdmember that all flight personnel and deck crew who wear glasses should have at feast two
pairs of corrective Imsm. Obviously, if the only pair of passes is miisplat^d, then the person is
incapable of performing his duties safely until new glasses are obtained. It is the medical
department's tesponsibihty to insure that these individuals do have an extra pair of corrective
lenses.
The only authorized lenses for flight personnel are the FG (flight go^le)-58, either in the
dear lenses or sunglasses.
Pilots and NFO's should not be allowed to wear polarized glasses. Canopies and windscreens
may also have a polarizing effect which can result in "scotomas," a very hazardous condition.
Pilots also should be advised against wearing the photosensitive type of sunglasses because they
do not offer enou^ protection from sunH^t. These lenses contain chromium and change to a
^^feer cdo£ wbenjeiiposed'to sun^t; however, the tint is not sufficiently dense to filter out
enou^ of iiie rays of tt^t to protfecftijlihe retina from glare.
9-4
Ophthalmology
If a cycloplegic refraction is performed on aviation personnel, they should be advised that it
will be necessary for them to be grounded from 24 to 48 hours. They must be examined prior
to flying again, and their pupils and accomihodation must have tetutned to normal limits.
The FUght Surgeon must remember that many aviators might* have m&M visual '^f^'ets
Which ^ould be corrected with lenses, btlt due to fear of beirtg'^gfotinded or being Jilaced in
another service gfoup, they wSl continue to squint md have less than optimum vim^i^euity.
Tlw TO^t Surgeon is encouraged to instill confidence in these people - to reassure them that
he is there to help them and make tiiem safer pilots - not to ground them or to chsuige liieir
service groups.
The Dissatisfied Refraction Patient
A certain percentage of patients who obtdn new spectacles will have some eompldnt. Many
times tifls is due to small changes in the new jji^scription md the fact that the patient has not
worn the spectacles long enough to get used to them. Spectacles with more plus lenses
frequentiy take several days of wear before they are accepted.
To verify tihat the ptesemption of a patient's spectadei is flie same as that *wfiieh was
oardCTedi ohi slioiild take the following steps. •
1. Lensometer reading on the new s^fictadeg, l^iese readings usually reveal the prescription
to be correct. Only a small percentage of errors are made in filling prescriptions. Acceptable
tolerances from the optical laboratory, which will cause no problems and should be accepted as
optically correct, are as foUows:
a. The sphere power can vary as much as .12 diopters on either side of what was ordered.
b. The cylindrical power can vary as much as .12 diopters on either side.
c. The cyUndrical axis can vary as much as 5 degrees on cyhnders of 1.00 diopter or less; for
larger cyhnders the axis variance should be 3 degrees or leas.
d. The optical centers should be within 1-2 mm of the measured interpupillary distance
(IPD).
2. Distance checked between the optical centera. This shditld be within 1-2 mm of the IPD.
If off by more thatn 2 ^16, this could contiteivabfy eatige prisatotte- pi-oblems. If the opti^
centers are found to be off, and this is felt t6 be the problem, |noth#f ^df of ipectacles mtmt be
ordered.
3. If steps (1) and (2) are found to be correct, then a repeat refraction is indicated to nile
out an error. The most common error is one of prescribing too much minus sphere or not
enough plus sphere.
U.S. Naval Flight Surgeon's Manual
The above steps will determine whether or not a patient's complaints are caused by optical
problems. If the patient does have what was ordered and the refraction is correct, and yet the
patient mii&meB to have symptoms, then it-'W^uld be appropriate to have Mm evaluated by
someone else. However, it is. not micommon for the ophthalmol<^ consultant to find that the
examining Fli^t Surgeon was correct in his refraction.
A small error in a refraction resulting in an airman wearing Sfpectacles which are not exactly
perfect will in no way cause harm to his eyes, nor should this small error result in a dangerous
flight situation, as long as the visual acuity is 20/20.
Trauma and Ophthalmologic Emergencies
Abrasions and Foreign Bodies
Minor trauma to and about the globe usually results in superficial corneal abrasions. A
corneal abrasion can easily be diagnosed by using a strip of fluorescein with some topical
opthetic to stain the cornea. When the excess is washed, the area of denuded cornea will show
up as a yellowish green area. Treatment of superficial corneal abrasions consists of patching the
eye for 12 to 24 hours after instilling a broad spectrurn antibiotic. The purpose of the patch is
to keep the eyelids from blinking and rubbing the cornea. The patch should be tight enough to
prevent this and usually requires 6-8 pieces of tape. HeaUng of the defect occurs by sbding of
new epithelium from the conjunctiva and by mitosis. Most abrasions heal within 12-24 hours.
Remove the patch the following day and examine the patient. If the defect is almost healed,
then broad spectrum antibiotic drops should be used for five to six days.
When a corneal foreign body is encountered it can be removed easily. The patient should lie
on his back and be made comfortable. Instill ophtiietic drops to the involved eye, and have the
patient fixate an overhead target with the non-involved eye. In many cases the foreign body
may be touched with a sterile applicator stick and this will dislodge it. If the foreign body is
embedded, a sterile 26 gauge needle or other sterile instrument, such as a spud or dental burr
may be used. The foreign body may be lifted out by the point of the instrument. A broad
spectrum antibiotic ointment should be instilled and the eye patched for 24 hours. Topical
antibiotic drops ^oqld be applied' for 3 .to .5 days. A rust ring,4f present, indicates: ferrous
material and oxidation; the rust ring should be removed with the foreign body, but if it cannot
be removed, the eye should be patched and the remainder of the rust ring removed the
following day. A small rust ring will absorb over a period of days.
Most abrasions and foreign body sites will heal with no further problems. Treatment is used
to prevent the rare case of infection leading to a corneal ulcer.
9-6
Ophthalmology
Lid-Skin Lacerations
Lacerations of the lid and the skin of the eyelids should be cleaned and primarily repaired
with small interrupted sutures such as 5-6 0 silk or dacron. The Flight Surgeon can confidently
close most lacerations involving all but the margin of the lid. If the laceration involves the lid
margin, and the services of an ophthalmologist are available, the eye should be patched and the
patient referred to the ophthalmologist. If the Flight Surgeon has to do the primary repair, the
edges should be approximated as closely as possible and small sutures used. Due to the good
vascular supply and the elasticity of the Uds, lacerations heal quickly. The sutures should be
removed on the fourth to fifth post-op day.
Canaliculus
If a laceration through the upper or lower canaliculus is noted, it is recommended that the
patient be referred to an ophthalmologist for repair. If no ophthalmologist is available, a small
polyethylene catheter or a small silk suture should be inserted through the severed ends of the
canaliculus. The skin and hd margins should then be closed on either side with interrupted
sutures. The cathtter must be left in place for a minimum of 4 weeks.
Hyphema
Blunt trauma to the globe results many times in hyphema. This can easily be diagnosed by
gross blood in the anterior chamber. The blood usually comes from the iris and/ or ciUary body.
This blood wiU absorb in 2-3 days if a re-bleed does not occur. The recommended treatment to
prevent a re-bleed is complete bedrest with binocular patches and sedatives until the gross blood
has absorbed. If an ophthalmologist is available, the patient should be referred to the
ophthalmology service for admission to the hospital. If he is an aviator or NFO, he should be
grounded for approximately 2 weeks after the blood has absorbed. Re-bleeds do occur in
10-15 percent of the cases no matter what the treatment. Treatment of the re-bleed is continued
patching and bedrest. If the re-bleed is of such degree as to raise the intraocular pressure and
cause blood staining of the cornea, it is a serious ophthalmological problem. If a re-bleed is
encountered, it is strongly recommended that ophthalmological consultation be sought.
Fracture of the Orbit
X-rays of the orbits should be obtained to rule out a fractured floor when moderate severe
trauma in and about the orbit is encountered. Many times the patient may be asymptomatic,
but the X-ray will reveal evidence of a fractured floor. This is usually seen as a clouding of the
involved antrum which indicates either hemorrhage or herniation of the orbital floor into the
antrum. Another common finding with fracture of the floor of the orbit is diplopia and
restriction of that eye on attempted elevation. These problems should be referred to an
ophthalmologist. If conditions prevent this, it is recommended that the patient be treated
9-7
U.S. JNaval Flight Surgeon's Manual
syrnptomatically with tetanus toxoid and broad spectrum antibiotics and cool and wajm
compresses as indicated. Ht; may be referred to an ophthalmologist when the occasion arises,
but in no case may the fracture be ignored. Serious deformity may result in the future.
Laceration of the Cornea and/or Globe
When the cornea and/ or globe has been lacerated, the recommended treatment is to patch
both eyes and place the patient on his back. Medicine MAY NOT be instilled into the eye. He
should be evacuated to a hospital where ophthalmic services are available for repair. If an
ophthalmologist is not available, it is recommended that the patient continue to be treated
symptomatic ally until evacuation can be obtained. (Administer tetanus toxoid and broad
spectrum antibiotics.) Primary closure of corneal wounds have been performed as long as 36 to
48 hours after the initial injury vdth good results.
Chemicals in the Eye
Any foreign chemical in the eye should be considered an emergency. Most chemicals in the
form of solutions and/or powders are very irritating and toxic to the eye. The eye should be
irrigated at once. The best source of an irrigating solution is a sterile IV bottle of normal saline.
The tubing should be used to meter the flow. The patient should be placed on his hack and
ophthetic instilled in tiie eye; then a Corpsman should albwly irrigate with the sterile solution
for 1 5 to 20 minutes. Then the eye should be examined and the irrigation oontinued for another
15 minutes if a very caustic chemical was involved. Antibiotic drops containing steroids are
indicated for chemical burns to the cornea and conjunctiva.
Sudden Disturbances of Visual Acuity
Fortunately, si Jden loss of visual acuity is relatively rare. These disturbances occur more
often in the older age groups and are associated withhypertensive, arteriosclerotic, and diabetic
changes in the circulatory systems. A brief discussion of the more common causes follows.
Occlusion of the Central iletinal Artery
Occlusion of the central retinal artery or one of its branches which supplies the macular
region will result in almost immediate diminution and loss of visual acuity in the involved eye.
In young adults the etiology is usually an embolus or spastic occlusion of the central retinal
artery or one of its branches.
In older nge groups the term amaurosis fugax has been used to describe fleeting vision. This
condition results when moderate to severe arteriosclerotic narrowing of the interal carotid
artery exists, causing lowered blood pressure to the ophthalmic artery. The patient describes
gradual loss of visual acuity which persists for 2-3 minutes, then a gradual return of visual
9.8
Ophthalmology
acuity. The hypoxia causes no lasting damage and visual acuity usually returns to pre-occurrence
levels. When one suspects amaurosis fugax, determination of the central retinal artery pressure
by ophthalmodynamometry is indicated.
Total occlusion of the central retinal artery or a branch can be diagnosed by observing the
fundus and noting a pale area distal to the occlusion. Treatment is aimed at vasodilatation and
should consist of ocular massa^ and oral administration of priscoline. If an ophthalmologist is
available, retrobulbar injection of priscoline in a mixture of xylocaine without epinephrine is
used. The use of carbogen (a mixture of oxygen and carbon dioxide) for vasodilatation has been
recommended.
In general the treatment that can be administered by the Flight Surgeon is very little. If the
occlusion of a central retinal artery or its branch is total and it persists for more than 5 minutes,
it is unlikely that the involved retina vrill recover.
Occlusion of the Centred Retinal Vein
Symptoms of occlusion of the central retinal vein or one of its branches is much less sttAde^
in onset than occlusion of the artery. The loss of vision is due to edema. Causes of occlusion of
the central retinal vein are diabetes meUitus, glaucoma, periphlebitis, and compression of the
vein at the AV crossing by arteriosclerotic proceases. Usually the percentage of recovery from
vein occlusions is much better than arterial occlusions. The Flight Surgeon should make the
diagnosis by noting scattered hemorrhi^es throughout the fundus associated with a dilatated
venous sepient. Treatment usually consists of heparin followed by Coumadin in an effort to
stave off the further occlusion sites, and allow recanalization to occur.
Vitreous Hemorrhage
Vitreous hemorrhage is most common after trauma or rupture of a neovascular tuft in the
eye. The predominant cause of neovascularization is diabetes meUitus. The diagnosis is obvious
when viewing the fundus. It is noted that the vitreous is hazy with RBC's or contains gross
hemorrhage. Treatment should be bedjcest until fke bleeding ceases and consultation with an
ophthalmologist. The visual acuity will depend on the extent of the hemorrhage within the
visual axis.
Optic Neuritis
Optic neuritis frequently produces a rather sudden loss of central visual acuity. The patient
may have had a "viral-type illness" with headache and fever for several days previoti%.
However visual loss wi&out antecedent symptoms is also frequent. There may be some
retrobulbar pain on motion of the eye. Visual acuity is usually diminished anywhere from
20/200 to 20/40 or 20/50. Funduscopic examination usually reveals a completely normal optic
9-9
U.S. Naval Fii^t Sui^eon's Manual
disc in retrobulbar optic neuritis. In papillitis the disc is hyperemic but not elevated. In visual
field examination the blind spot is normal size but a centra! scotoma will be present. Clues that
are important in helping to make this diagnosis are a "Gunn pupil " one which shows a reduced
amtjunt of reaction to direct light, and disturbed red^green cplor perception in the involved eye.
This color disturbance can be deterrained by testing color vision monocuhtfly.
Treatment in the early phases is usually with systemic steroids on the order of 50-70 mg of
Preiinisone every other day. This should be continued for 7 to 10 days while following the
visual acuity of the patient, the most likely cause of optic neuritis is multiple sclerosis. If this is
the cause, visual acuity usually will start improving vnthin 3 to 4 days and many times will
return to a normal 20/20. Other causes of optic neuritis are toxins and/or infections from
adjacent tissues.
Centeal Serous Retinopathies
Edema and/or hemorrhage into the retina or subretinal area in the macular region describe
syndromes known as "central serous retinopathy." These syndromes are Hi-defined and have
diverse etiology, but are fairly frequentiy seen by the ophthalmologist. The patient is usually a
young adult under stressful situations. Diagnosis can be made by the symptoms of decreased
visual acuity on the order of 20/40 to 20/50. Associated with, this is metamorphopsia (alteration
in shape of objects). Careful funduscopic examination will reveid minimal edema and/or
hemorrhage and loss of the foveal reflex in the involved eye. The cause of this is thou^t to be
an autonomic nervous system imbalance causing vasodilatation and increased permeabihty of
the vessels in the macular region.
If hemorrhage is present, systemic steroids are commonly used. In the absence of
hemorrhage, steroids are usually not recommended because tiie course of the disease seems to
be unaltered either way. It is also recommended that vasoconstrictors such as nicotine, coffee,
and tea be avoided. Also, strenuous exercise should be avoided. Further, the patient should be
removed from any environment or occupation causing an unusual amount of tension. Visual
acuity will return to 20/20 in a large percentage of the cases. This condition lasts an average of 4
to 8 weeks.
Glaucoma
Because approxiniately 2¥t percent of the adult population has glaucoma simplex, the Fhght
Surgeon will probably have one or more people in his squadron who are under treatment for
this affliction. This will especially be true in the more senior aviators and in older enlisted
persormel.
9-10
ophthalmology
The recommended treatment for glaucoma simplex is miotics (cyclotonics) such as
pilocarpine. These people are usually begun on 1 percent pilocarpine q.i.d. to each eye. They
should be followed by an ophthalmologist at least every three to four months and have visual
fields and aceurate study of the optic discs performed at least once annually. As long as the
intraocular pressure (LOP) is undw control and the visual acuity i& corrected to 20/20 and there
are no significant visual field defects, aviators can fly in SG-IIL If a change to another Service
Group is desired, a request for a waiver should be submitted to BUMED. However, because the
miotic pupils prevent adequate dark adaptation, it would be unlikely that a waiver for SG I
would be granted.
Flight Surgeons conducting annual physical examinations should have the Coi|>8inpx check
the lOP in people who are 40 years of age or older or in those whose optic discs show unusually
large cups. Patients who have a family history of glaucoma or who have had a previous hi^ lOP.
finding should have their lOP taken no matter what their age.
The normal lOP raftge H from 13^18 millimeter of mercury. However, it is not uncommon
to find lOP's slightly W^r than this - ran^ from 19 to 23 mm. This de^e of lOP usuaUy
wiU cause no damage to the eye. However, an lOP ftndiMg greater than 23 mm should be
referred to an ophthalmologist for evaluation. This is no emergency unless the pressure is
extremely high. Many eyes will tolerate an lOP of 25-30 mm for years vkithout showing any
change in the optic disc or the visual field. These people should be i^owfed hf ah
ophthalmologist with careful study.
The trend by ophthalmologists at the present time is to **follow," rather than treat patients
with shght elevations of lOP. The use of miotics causes many undesired side effects, and unless
it is definitely estabUshed that the patient has glaucoma, it is best not to subject him to these
effects.
Use of the Tonometer
The preferred instrument in testing for glaucoma is the Schibtz tonometer. It is an accurate
and f airly simple instrumemt to use. It is recommended that &e squadron or wing FUght
Surgeon assi^ one or two Corpsmen the responsibility for taking the lOP. In addition, these
Corpsmen should clean the tonometer daily when in use. The recommended method for
cleaning the tonometer is to disassemble it and use pipe cleaners soaked in ethyl alcohol to clean
the barrel. Allow it to dry and then reassemble it. The use of a cotton ball moistened with ethyl
alcohol to clean the footplate ifetween pati^ts is recommeiided. The alcohol must be
evaporated prior to Use. If an irttraviolet lamp with a tonomester stand is available, is
recommended as safe use. However, a heat sterilizer should not be used; it is a potentiidly
9-11
U.S. Naval Elij^ Surgeon's Manual
dangerous instrument and many corneas have been burned by injudicious use of a hot
tonometer.
Any time an elevated lOP is discovered, the measurement Aould be repeated on another
visit. The most common cause for spurious elevations of lOP readings is faulty technique in
taking the pressure.
Acute narrow angle glaucoma is an ophthalmological emergency. This is the type of
glaucoma in which the iris blocks the anterior chamber angle and causes the lOP to rise to very
high levels. A patient with this disease will present with a painful red eye (this is a unilateral
condition), a steamy cornea, a semi-dilated pupil, and an lOP between 40-60 millimeters of
mercury. Treatment should consist of instiUation of 2 percent pflocffirpine c[ 30 minutes until
miosis occurs. This will clear the anterior chamber angle and allow the lOP to return to a normal
level. The patient should be referred to an ophthalmologist for further evaluation and probably
an elective peripheral iridectomy after the eye has become quiet. The fellow eye should also be
studied for need for an elective peripheral iridectomy.
Annual ntysical Examinations on Fli^t Personnel
In performing an annual physical examination on flight personnel and in correctly filling out
the StandardForm 88, a Fhght Surgeon wiU be required to evaluate the general ophthalmologi-
cal status including external exam, pupillaryreactions, andfunduscopic exam. In addition, deter-
mination of the near and distant visual acuity and tests for stereopsis are required. Also, in indi-
viduals who are 40 years of age or older, an intraocular pressure determination must be made.
When the near or distant visual acuity is found to be defective, a refraction must be performed
which proves that the visual acuity can be corrected to 20/20, thus ruhng out any organic dis-
ease. Glasses should be prescribed when indicated by visual standards and when desired by the
individual airman. When any change in Service Group is determined to be necessary because of
visual defects, the Flight Surgeon should counsel the airman involved and make him aware of
the change in his flight status that is to be recommended. If the Flight Surgeon is not sure as to
whether or not to recommend a change in Service Group, he should consult with his Senior
Medical Officer or call someone more experienced for advice. Changing an airman's service
group because of visual defects that are marginal should be avoided if possible. If tfie airman can
fly safely with corrective lenses, a waiver or other ajpipropriate action Should be taken.
The determination of phorias is not mandatory on an annual basis. However, if symptoms of
unusual blur or diplopia are present, determination of phorias is indicated. A significant change
from previous existing phorias indicates' some abnormality in the extraocular muscles and an
ophthalmological consultati<w should be obtained.
9-12
Ophthalmology
Color vision determination is not required annually but should be performed if symptoms of
color deficiency are present. Acquired color defects are rare but do occur.
When the physical exam has been completed, the Flight Surgeon should ascertain that the
visual acuity requirements for the specific service group are met. A Standard Form 88 must not
be forwarded to the Bureau with conflicting visual acuity records re^irding the recommended
service group- This will result only in the Standard Form 88 being returned for further
amplification.
Eyewear for Navy Personnel
The BuMed Instruction 6810.4 series states where and how to order spectacles for eligible
personneL A copy of this is available in medical departments.
At the present time, the appropriate facility issues spectacles to eligible personnel on receipt
of a Standard Form DD-771. This form must be properly completed and must have the
prescribing physician and the aufhoiizmg physician's name on the request.
The Navy has two basic types of spectacle frames. One is a black plastic frame, known as the
S-10 frame, and is available to all eligible personnel for correction of refractive errors.
The second type of frame issued by the Navy is the "FG-58 (flying goggle)." This is a
gold-coated frame with adjustable nose pads and flat temples. These frames are available only to
personnel in a flight status or those who work on the flight deck and are authorized this
eyewear by appropriate BuMed Instructions. Lenses in the FG-58 goggle can either be clear or
tinted. The neutral gray sunglasses filter out approximately 87 percent of the vidble light, tiius
insuring adequate protection agaipst glare-causing photophobia, yet allowing enough Ught for
good visual acuity on average daylight days. The FG-58 is the only sunglass authorized for
flying.
There are other colored and tinted spectacles on the market which some aviation personnel
like to wear but they all have shortcomings compared to the FG-58. The photo-sensitive lenses
(those containing chromium) change to a dark shade on exposure to light. However, tiiis shade
is not dark enough for adequate protection from the sunlight encountered m flying aircraft.
Pilots and other flight personnel should be educated on the shortcomings of these glasses and
should not be allowed to wear these while flying. They will be subject to glare and photophobia.
9-13
U.S. Naval Flight Surgeon's Manual
Polarized lenses are also occasionally obtained by flight perSotmel and worn without
authorization. The hazards with polarized lenses are great. Occasionally the canopy (windscreen
of the aircraft) and visors will have polarizing effects, which, combined with the polarized
glasses, will result in scotomas (bhndspots) and will be exceedingly dangerous to the safety of
the flight personnel. No flight personnel should be allowed to wear polarized lenses while flying.
All lenses now issued in both the S-10 frame and FG-58 frame am made of plastic. The
cyhnders are ground in the minus form, and the fabricating facihty will accept the prescription
with cylinders written in the minus form. The advantages of the plastic are the Hght weight and
the safety against shattering. The disadvantages of the plastic are that they scratch very easily
making the life of the spectacles less than those of glass. Personnel should be educated as to the
proper care. A set of instructions comes with each issue.
Only personnel on flight orders are eligible for the FG-58. It is the Fhght Surgeon/ AMO's
responsibihty to insure that only ehgible personnel are ordered the FG-58. Because the price of
gold has 'skyrocketed' in the past few years it is doubly important that only eligible personnel
receive the fhght goggles. The best way to ascertain ehgibilify is to require a copy of an
individual's flight orders prior to ordering the spectacles.
Contact Lenses
BuMed Notice 6110, dated 17 November 1975, authorized Class n aviation personnel to
wear contact lenses. A copy of this instruction is available in ffledieal departments.
Briefly, this notice states that Class 11 aviation personnel (those not in actual control of the
aircraft: NFO, FS, etc.) can at their own discretion wear contact lenses in duties involving
flying provided the contact lenses correct the visual acuity to 20/20, and the individual has on
his person an appropriate pair of spectacles as a 'backup.'
Obviously, the wearing of contact lenses will result in a number of corneal abrasions, lost
lenses, and incidences of spectacle blur which will cause the individual to seek the aid of a Flight
Surgeon. Information on contact lens problems can be found in the appropriate references.
In general, the problems of the contact lens wearer will fall into one of the following
categories. A brief discussion of 'how to handle' the problem follows.
1. Corned abrasions
2. Spectacle blur
3. Lost or broken lenses
9-14
Ophthahnologf
4. Problems with cleaning the lenses
5. Other
Corneal Abrasions
These should be suspected wfeen a patient complains of discomfort or a fo*agn body
sensation after wearing the lenses. This problem can best be diagnosed by using fluorescein to
stain the cornea. This will appear as a yellowish -green stain in any area where the epithelium of
the cornea is lost or damaged. Treatment is described under abrasions and is aimed at allowing
the epithelization process to occur. The wearing of the contact lenses should be discontinued
for 3 to 5 days after total healing has occured. Wearing time after healing should be gradnally
increased.
Spectacle Blur
This term refers to blurring of the visual acuity even with corrective spectacles in place after
an individual has taken out his eontaet lenses. Tbe cause of this is corneal edema and/or a small
amount of irregular astigmatism. Usually the best visual acuity obtained by refraction and
spectacles is 20/30 or 20/25. The blur persists for one to three days, usually until the cornea
returns to normal. This blur is common in conLact lenses wearers and most of the time does not
cause complaints. However, in the aviation community where 20/20 visual acuity is necessary, it
can pose a problem.
Patients who eompMu of spectiicle blur should be refracted immediately after rcm<ning
their contact lenses. The required correction at this time may be different from that necessary
several hours later. In some instances certahi aviation personnel may require two pairs of
spectacles - one to wear for 1-2 hours immediately after reWioving the contact lenses, the
second pair to wear several hours after the lenses are removed.
Speetacle blur is one of the disadvantages of contact lenses, with most wearers experiencing
this blur at one time or another. If it becomes increasingly symptomatic, the contact lenses
should be checked for adequate fit to insure that "orthokeratology" is not being performed
unintentionally. For fUght personnel who have this problem in large degree, it is recommended
that the Flight Surgeon encourage them to discontinue their contact lenses and fit them witb
corrective spectacles after the corneas return to normal. It is further recommended that they
discontinue wearing the contact lenses until they have been checked by an ophthalmologist or
optometrist.
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U.S. Naval Flight Surgeon's Manual
Lort or Broken Contact Lenses
Most contact lenses wearers will at one time or another lose or misplace their lenses or chip
one, thus requiring a replacement. These lenses should be replaced only if the patient has a
fairly recent prescription with which he is happy and has obtained 20/20 yiiual acuity. A
replacement lens using his prescription could be ordered, but it is necessary that these lenses be
purchased through a Navy Exchange with a contract with the optical company. Hi^er
authority has forbidden the individual physician to obtain lenses from an individual company
on a cash basis.
Problcims with Cleaning the Lenses
Most contact lenses wearers begin by being very conscientious in the hygienic care of their
lenses. They follow the recommended procedure for using cleaning and wetting solutions.
However, as time progresses, they take shortcuts and many times this causes oily material and
other matter to build up on the surface of the contact lens. This causes the contact lens wearer
to experience fluctuating visual acuity. The problem can easily be diagnosed by viewing the
contact lenses under a magnifying glass or sht lamp. The solution to the problem is to reinstitute
the daily hygiene originaUy recommended. The Navy does not stbck cleaning and wetting
solutions, and it is up to the individual to procure these from private sources.
Other Problems With Contact Lenses
There are many other problems with contact lenses, some minor and some major enough to
require recommendation that the patient cease wearing contact lenses. It is impossible to
enumerate all the problems possible, but in general it is recommended that the Flight Surgeon
use common sense in dealing with patients who do wear these lenses. Obviously some myopic
NFO's will want to wear contact lenses but due to highly sensitive eorneas and tight hds will be
unable to wear them except for short periods of time. It is recommended that these people not
wear contact lenses. Other patients will wear contact lenses for a number of months quite
successfully. Then for reasons unknown they develop symptoms of burning, photophobia, and
discomfort. This is thought to be an acquired sensitivity. After ruling out pathology, if the
symptoms persist, it is recommended that these people cease wearing contact lenses.
It is recommended that older people who have had long-standing refractive errors not be
fitted with contact lenses. The success rate for these people is very low. It is most likely that
they want to try them for cosmetic reasons, and ophthalmologic experience bears this out.
9-16
Ophthalmology
Any time the FUght Surgeon encounters a contact lens problem which he cannot identify,
he should recommend that the wearer discontijme using the lenses for several days. Many ime&
the answer to the problem will then make itself known.
Perceptual Disorders
Visual Illusions
Visual illusions and other disorientation phenomena have been categorized by investigators
relying on information from pilots and research subjects. 'Hieae phenomena are important
because in certain situations normal visual inputs cause djnormal sensations on the part of fhfe
pilot. Most of these illusions are experienced when visual acuity is decreased by disturbances
such as darkness, rainfall, fog, haze, or the pull of gravity on the ocular system. Not all pilots
experience these illusions, but they are frequent enough that the Flight Surgeon should be
familiar with them and be able to discuss them intelligently. The exact cause of these illusions is
not completely understood, but the fact that they do odcttr and present hazards to the pilot
shotild be appreciated.
Autokinetic Illusion. An individual in virtually total darkness, observing a fixed point-source
of light, will report seeing the hght move. Individuals also have reported such movement when
viewing a stationary black target against a homogeneously illuminated visual field. Such
apparent movement of a fixed spot of light is known as autokinetic illusion. In the appropriate
set of circumstances, most people will experience such movement. The autokinetic effect can,
and does, produce a very dangerous sitoiation during raght flying. There have been reports in
which frilots have followed lights on the ground, thinking these Ughts were from other planes
untQ they were almost directly over the li^ts.
The autokinetic illusion can be attributed mainly to flie involuntary movement of the
muscles that control Hie eye. Under normal conditions, the perception of parent motion of an
object is controlled by other objects in the visual field. During n^ht flying, the visual field is
impoverished, and small h^t sources appear to move of their own accord. Inasmuch as training
is ineffective against the autokinetic ittusion, aviators must understand its operation and must
learn to deal with it as it occurs.
Oculo-Agmvic lilmion. The oculo-agravic illusion has been demonstrated in aircraft in
conditions which produce brief periods of reduced or zero-gravil^ forces. As an aircraft enters a
zero-G pardjoHc maneuver, a fixed visUial target will appear to rise. When the aircraft reaches the
zero-gravity phase, the target moves downward, with a subsequent rise again during the recovery
pullout.
9-17
U.S. Naval Flight Surgeon's Manual
Prism Effect. Distortion of images has been reported by a number of pilots when viewing
objects throu^ a windscreen covered with rain. The cause of this is a surface of water which is
thicker near the bottom causing a prismatic effect, Wh^n the pildt looks fhrough this, he, in
effect, is looking through a base-down prism which tends to make objects look higher or closer
to him than they reaUy are. This causes errora in distance and height judgment and can be
critical during landing or recovery aboard ship.
Waterfall Effect. A few helicopter pilots have experienced this illusion when hovering or
when in slow flight at low altitudes over the surface of water. The downward Mast of wind from
the rotor blades causes the air to pick up water and to di^lace it upward. A pilot might look
out of his cockpit and see drops of water going upward in his field of virion. This would cause
disorientation in his attitude and might cause him to make a corrective maneuver resulting in his
descending into the water.
tlUi
Sloping Runways. Sloping runways can cause illusions in altitude judgment for airmen
attempting to land. When the runway slopes away from the touchdown end of the runway,
visual cues tend to make the pilot come in high and land long. If the runway slopes toward the
touchdown end of the runway, visual cues tend to make the pilot come in lower than he should,
with the chance of landing short of the runway. Airmen should be advised to monitor their
altimeter closely when landing at airports having runways of this nature.
Pilot Fascination
Faaeination is defined as a condition in which the pilot fails to respond adequately to a
clearly defined stimulus situation despite the fact that aU of the necessary cues are present and
the proper response available to him. An earlier study of pilot experiences with fascination
(Clark, Nicholson, & Graybiel, 1953) classified these experiences into two categories:
Type A fascination is fundamentally perceptual in nature. The individual concenti'ates on
one aspect of the total situation to such a degree thiit he rejects other factors in his perceptual
field. "Target" fascination is of this type and has been a fairly frequent cause of aircraft
accidents. The pilot becomes so intent on hitting the target in an air-air gunnery run that he fails
to observe the tow cable and collides with it. On an air-ground mission, he may become so
intent on getting his bomb on target that he fails to observe his altimeter and pulls up from his
dive too low. The following is an example of Type A fascination:
My instractor Was teaching me how to make emergency
landings on a small field. 1 had made one or two tries and hadn't
been yery successful. The next time 1 was determined to make a
good approach. Both the instructor and 1 were so completely
9-18
ophthalmology
engrossed in the task that we failed to hear the landing gear
warning horn. Consequently, we landed with the wheels in the up
position.
In Type B fascination, the individual may perceive all of the significant aspects of the total
situation, but still he unwilling or unable to make the proper response. The following h m
example of Type B fascination:
1 went into a skidded turn stall during a small-field shot. I
knew I was in unbalanced fli^t during the last turn, but as I
recall, I was so determined to get a straightaway before hitting
the field that I didn't seem to care what happened. The plane
stalled and the instructor took over.
Fascination has apparently been experienced by virtually all military pilots. The aviator must be
made aware of such hazards and periodically reminded of them.
Although illusions and/or other disorientation phenomena are not as prevalent in the cause
of accidents as the lack of scanning and poor depth judgment, they are potentially dangerous.
Flicker Vertigo
An unusual pilot response to a steady light flicker is occasionally encountered. Despite its
rarity, the Flight Surgeon and all pilots should be aware of it and its devastating effects. A
steady light flicker, at a frequency between approximately 4 to 20 Hz can produce unpleasant
and dangerous reactions in normal subjects, including nausea, vertigo, convulsions, or
unconsciousness. The exact physiological mechanisms underlying such reactions are not known.
However, it is believed that susceptibility is increased when the pilot is f ati^ed, frustrated, or in
a state of mild hypoxia. The following is a dramatic report of the manner in which flicker
vertigo can occur:
After flying for some time at an altitude of 16,400 feet, a pilot in
a single-seater propeller aircraft made a perfect landing. However,
he did not taxi the plane to the hangar. Instead, the plane
remained motionless, its propeller revolving slowly. The pilot was
found bent over the controls, unconscious.
At first, it looked as though the pilot had not used his oxygen
mask. However, in this case, the pilot had lapsed into uncon-
sciousness after making a good landing.
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U.S. Naval Flight Surgeon's Manual
The rays of the low-lying sun were shining on the slowly turning
propeller blades. Refleeted flashes of lig^t were being thrown on
the pilot's face at a rhythmic rate of about 12 per second.
In a study of 102 Navy helicopter pilots, researchers attempted (1) to determine the
incidence of flicker vertigo or flicker problems during actual flight operations, and (2) to
determine if any helicopter pilots in an operating squadron would reveal undue sensitivity to
light as shown by marked EEG changes or unusual subjective sensations during exposure to
photic stimulation in the laboratory. One-fourth of the pilots reported flicker during flight as
annoying or distracting but in only one instance was a near-accident attributed to flicker. None
of the EEG responses of this group to photic stimulation could be clasdfed as even borderline
abnormal. Photic stimulation thus does not appear to be a useful device to detect those who
would show abnormal EEG activity during flicker. Photic stimulation, however, did identify
pilots who had subjertivc feelings of discomfort during the flickering Hght. In addition, and
perhaps of considerable importance, photic stimulation identified 22 pilots who became drowsy
fflid showed lowered alertness during the period of stimulation.
Night Myopia and Ni^t Presbyopia
Night myopia, also known as twilight myopia, is a phenomenon which causes some
individuals with a small degree of myopia in dayKght to become more myopic after dark and to
have moderate symptoms of myopia. As an example: A pilot with 20/20 visual acuity in
normal daylight hours with a piano to a -0.25 sphere refractive error in each eye may develop
unaided vision of 20/30 to 20/40 in each eye and a refractive error of as much as -0.50 to
-0.75 sphere. This condition can result in symptoms which would be hard to define unless the
examining FKght Surgeon thinks of night myopia.
The Purkinje Shift, chromatic aberration, spherical aberration, and ciliary spa&m are factors
which contribute in varying degrees to night myopia. An airman who has symptoms compatible
with night myopia should be evaluated thusly. First, his visual acuity should be checked on the
Armed Forces Vision T^ter or in a WeU illuminated eye lane with a Snellen Chart. Usually the
values wUl be 20/20 or sHghfiy less. Then the eye lane should be darkened (except for the
Snellen Chart), and his visual acuity rechecked after allowing him to sit approximately 3 to
5 minutes to allow the pupil to dilate. Many times the examiner will be surprised to find that
now the visual acuity is two lines less than it was previously. The airman should be refracted in
the dim illumination, and one will usually find more myopic error. Prescribe this myopic
correction for night flying.
9-20
Ophthalmology
Night myopia should not be over-diagnosed. If a refractive error shows a»derate amount
of plus sphere during normal lighting condiMonB, then the development of night myopia is
unlikely.
Night presbyopia, also known as red light presbyopia, occurs in presbyopic individuals when
subjected to red hght. This is frequently encountered in the cockpits of aircraft during night
operations. Red light has the longest wavelength of all lights in the visual spectrum. When
tries to read instruments or charts in red Ught,the demand for accommodation is more thaiiif
one were using white Ught. This causes difficulty reading small print in presbyopes. When
airmen complain of these difficulties, it is usually wise to prescribe a pair of flight glassei with a
stronger add for night operations than the add indicated for day operations.
Space M^rfefiia
The term space myopia is used to describe the myopia experienced by airmen when there is
'nothing to look at' outside the cockpit. One example of this would be the pilot who is flying
VFR on top. The clouds prevent him from seeing the ground, and the li^t reflected from the
cloud layer beneath his aircraft puts him in an environment where there are reduced vismal mm,
His eyes, having iiothi!B| else to focus on, will tend to 'lock-in' on the aircraft instruments and
remain fixated for this distance. When he looks outside the cockpit, his eyes remain fixated for
near distances because there are no targets for him to observe. This myopic situation could
cause him to be unable to see other aircraft when they would otherwise be seen. To .attftfiate
this myopia, it is recommended that an airman look at the win#ipg of his aircraft from timt
time to allow relaxation of his cihary muscles. Also, in formation flight, the aircraft should
change lead to give those behind a target to observe.
Topics of Iiiteriest for Safety Lectures
Scan and Avoidance of Midair Collisons
Most midair collisions occur in dayhght VFR conditions, which should offer a safe
environment for flying. Obviously, then, there must be contributing factors which fcafl td
midair eoffisions other Hian bad weather and podr visihiUty. Analysis of aircraft accidents
(midair coUisions) have borne out the fact that most of these collisions occur in high aircraft
density areas such as military training areas, civilian training areas, at the perimetry of high
density airports and at other airports, and over frequently used navigational aids. Most of these
occur at low level altitudes (below 3000 feet agl) when the hemispheric rule of flight is not
observed. The most frequent cause cited hy aircraft in^reatigation boards for these midair
coUisions is the failure of the old adage ^'See and Be Seen." In other words, the pilot of one or
9-21
U.S. Naval Flight Surgeon's Manual
the. Other or hmih of the aircraft involved fail to continue to use a good scan pattern. They
became eomplacent or preoccupieil with flying thb Mmmtt and flew into one another.
A good scan technique requires good central and peripheral visual acuity, freedom from
glare (by correct usage of sunglasses and/or visor), and a windscreen.or canopy elear of dirt,
moisture, and scratches. In addition, the individual performing the scan must be mentally alert
mA feel well physicaUy to do an adequate job. Fatigue, hypoxia, hangovers, or any medications
which might interfere with mental alertness should be avoided when flying.
The Aviation Safety Officer (ASO), instructor pilots, and F%ht Surgeon must continually
emphasize the importance of good scan techniques. They must emphasize that of all factors
available, the "See and Be Seen" philosophy is the greatest aid to safe flying. The ASO of each
squadron usually has information and pictorial displays depicting how a good scan should be
performed. This should be the topic of frequent safety lectures. The Flight Surgeon can present
information on the need for good visual acuity and other health factors.
Approach and Landing Accident
The largest percentage of aU' aircraft accidents occur in the approa<A4anaing phase of flight.
This refers to military aircraft, commercial air carriers, and civiHan pleasure/business aircraft.
Experienced aviators appreciate this phase of the flight as being the most dangerous. Factors
contributing to this dangerous situation faU into two categories: The first belongs in the
category of flying the aircraft. More attention and skill is needed in control of the aircraft
during this phase of flight. The second category falls in the visual clues or lack of visual clues in
performing a successful landing.
Factors involving controlling the aircraft are: transitioning from a straight and level flight at
altitude to a flight which is descending, slowing, and making frequent changes in headings. In
addition to this the pilot must establish communication with approach control and/or the
control tower. He must 'set up' the aircraft to make the appropriate type of approach and
prepare the aircraft for contact with the ground (runway). The pilot also must be prepared for a
missed approach. The successful performance of this phase of the flight requires a tremendous
amount of attention on the part of the pilot. All of these factors, plus the higher density of
traffic, contribute to the inherent danger of the landing phase.
The second important aspect of landing concerns the use 6f visual dues. The pilot must
judge accurately his height above the terrain, distance to touchdown, and speed of the aircraft.
These are learned uses of visual information which come from many hours of flight time and an
understanding of the binocular and monocular clues to distance judgment. Conditions which
9-22
Ophthalmology
interfere with visibility such as darkness, clouds, haze, rain, fog, etc., contribute to a lack of
visual clues at this phase of flight. Obviously this phase of flight is most demandlcg^^lihwiltfb
and attention required of the pilot and the flight crew.
A good discussion of clues to depth judgment and other factors can be found in the
excellent article written by Robert H. Riordan, MD of the Medical Department of
TWA: "Visual Perception in Approach and Landing Accidents," presented at the International
Air Transportation Association in Istanbul, Novehiber 10-15, 1975, Dr. Mordpl aftalyzed air
carrier accidents throughout the world from 1962 to 1974. He found that im 196 afe ©urtiejr
accidents, fifty percent occurred during the approach and landing phases of flight, and
seventy -five percent of these occurred at night or in rain and IFR conditions when visual clues
to depth judgment were decreased or absent. In twenty-five percent of the accidents, pilot
misjudgment of distance, altitude, or speed were factors in causing the accidents.
Dark Adaptation
The Flight Surgeon will frequently be called on to lecture airmen on the importance of mi
the technique for dark adaptation. "The mechanisms of dark adaptation are, of course, well
known to medical personnel, Mote, hdwever, should be reminded of the time - approximately
30 minutes - to achieve complete dark adaptation. Factors in aviation which enhance dark
adaptation are the avoidance of white light through use of red goggles or red lighting in the
ready room. Other factors are avoiding smoking and the use of 100 percent oxygen in the ready
. .""v ' ■ . • II.. '
room and in the cockpit of the aircraft. .
Obviously all night flights do not require total dark adaptation, but in many situfitiotis, Stl#
as maneuvering aircraft on a dark carrier deck, dark adaptation is quite important.
BiUiography
General Ophthalmology
Ellis, P.P., & Smith, D.L. Handbook of ocular thempeutics and pharmacology (4th ed.). St. Louis: Mosby, 1978.
Scheie, H.(;., & Albert, D.M. Adler's textbook of ophthalmology (8th ed.). PhUadelphia: Saunders, 1969.
Vaughan, D., & Asbury, T. Gmerid ophthalmology (7th ei). Los Altos, California: Lange Medical Publica-
tions, 1974.
^fraction and Lenses
Sloane, A. Manual of refraction (2nd ed.). Boston: Little, Brown and Co., 1970.
Tratuna and Ophthalmologic Emergencies
Combos, G.M. (Ed.). Handbook of ophthalmologic emergencies. (Medical Handbooks). Flushing, N.Y.: Medical
Examination Publishers, 1973.
Scheie et al. op. cit.
9-23
U.S. Naval Flight Surgeon's Manual
Sudden Disturbances of Visual Acuity
Vau^n et al. op, cit.
Glaucoma
Scheie et al, op. cit.
Annual Physical Examinations on Flight Personnel
Department of the Navy. Manual of the medical department, U.S. Navy (NAVMED117). U.S. Government
' Plinth^ Office.
Perceptual Disorders
Anonymous. Notes from your flight surgeon. Approach, (Naval Aviation Safety Review), 1956, 2, 33.
Qark, B., Nicholson, M.A., & Graybiel, A. Fascination: a cause of pilot error. U.S. Naval School of Aviation
Medicine, Proj. NMOOl 059.01.35. Pensacola, Florida, May 1953.
Johnson, L.C, Flicker as a helicopter pilot problem. Aerospace Medicine^ 1963, 34, 306-310.
£7.5. Naval Flight Surgeon's Manual. Prepared by BioTechnology, Inc., under Contract NONR-46 13(00), Chief
of Naval Operations and Bureau of Medicine and Surgery. W^ington, D.C., 1968.
t
Topics of Interest for Safety Leetnres *
Riordan, R.fl. Visual perception in approach and landing accidents. Paper presented at the Intemational Air
Transportation Association Meeting, Istanbul, November 10-15, 1975.
Additional Reconunended Reading
Duke-Elder, S. (Ed.). System of ophthalmology series. (15 vols.). St. Louis: Mosby, 1958-1972.
Physicians' desk reference for ophthalmology. Oradell, N.J.: Medical Economics Co., 1976/1977 Edition.
Stem, H.A., & Slatt, B.J. Ophthalmic assistant: fundamentals and clinical practice \(3rd ed.). St. Louis: Mosbv
1976. f \ / X,
9-24
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CHAPTER 10
DERMATOLOGY
Introduction
Aircraft Carrier "Mystery Rash"
Skin Complications Due To Environmental Factors
Additional Common Dermatological Diseases
Differential Diagnosis — Treatment Guide
Dermatology Medications
Introduction
Approximately 50 percent of the sick call problems aboard an aircraft carrier are
dermatologically related. There are several factors that could contribute to this high figure,
including age group, adverse environmental factors, motivation of the patient, and; the
recalcitrant nature of dermatological disease itself.
Deploying medical departments should send their laboratory technicians and a sick call
corpsman to be learning participants at the dermatology clinic at the nearest large naval hospital
for two to five mornings of active duty sick call. They will see nearly every dermatology
problem that they wiU encounter while deployed and have opportunities to review and perform
the KOH Ptep, Scabies Prep, and the darkfield examination.
It is recommended that the medical department's Ubrary be reviewed prior to deployment.
The sixth edition of Diseases of the Skin by Andrews and Domonkos is complete enough to
adequately inform the Flight Surgeon about any of the rare or unusual dermatological diseases
that he may encounter. Additionally recommended are the following thfee atlases from the
Year Book Medical Publishers in Chicago: Color Atlas of Dermatology, Color Atks of
Infectious Diseases, md Color Atks of Venereology.
This chapter will not discuss venereal diseases since they are covered in chapter 11.
Aircraft Carrier "Mystery Rash"
There is no such entity as a strange, contact dermatitis seen only aboard ships which seems
to clear up after, a short liberty period on the beach, air evacuation to Germany, or awaiting a
dermatology consultation at a naval hospital. Most frequently this rash is miliaria rubra or "heat
10-1
U.S. Naval Flight Suregon's Manual
rash." The heat and humidity associated with many of the work and living spaces aboard ship
cause the tropical-hke heat rash. The task is frequently aggravated by overtreatment, bathing,
and soaps. It is best trealsd by removing the individual from the heat stress area and
recommending that the patient change clothes frequently, wear only cotton materials, and avoid
prolonged bathing or soap exposure.
The normal skin has a pH of 5.5. Many soaps are alkali and often in the pH range of 12
to 13. Many of the "deodorant" soaps contain antibacterial a^nts which can cause a contact
irritation allergy or photoallergy; the maceration of constant high humidity, coupled with
incomplete rinsing, produces an exaggerated percentage of such reactions. "Irish Spring" is one
of the most irritating soaps in use. Individuals with "dry" or "normal" skin should reduce the
frequency of bathing, decrease the temperature of bath water and duration of showers, and use
one of the soap substitutes, such as Loi^oUa, Basis, Casteel, Oilatum, Aveeno, or Alpha Keri.
Skin Complications Due to Environmental Factors
For many of a carrier's inhabitants, the working conditions are unaffected by the weather.
Their working spaces will remain a heat stress area even whUe in Arctic waters, and there will
dways be crowded berthing conditions. Acne, contact dermatitis, fungal and bacterial
infections, and other dermatological conditions are caused or aggravated by the heat and
humidity, and a scabies or crab louse infestation can go through an entire berthing area. The
following conditions are seen in a much higher percentage aboard a carrier than at an air station
dispensary.
Scabies
During a recent worid-wide epidemic* of scabies, the condition was the most frequently
misdiagnosed disease seen by a dermatologist. The obvious clues are intense pruritus, especiaUy
at night, and the affliction of other family members or sex partners. The classic scabies
distribution is on the glans penis, finger webs, and elbows. It is rarely seen on the face. It
requires approximately four to six weeks after skin exposure to develop symptoms, and the
disease always responds to topical gamma benzene, commerciaUy known as KweU. Treatment
failures occur when there is deviation from the recommended procedure, which is the
application of KweU to the entire body from the neck down after bathing, and leaving it on the
body for 24 hours before washing again. AU bed sheeting and clothing should be freshly
laundered. The same procedure should be repeated within two to seven days. The patient is
likely to continue to itch for several weeks after treatment and may suffer some degree of
parasite phobia for months. Occasionally, a secondary bacterial infection may develop from
excoriation, or the patient may reinfect himself from a friend or animal. A patient may be
10-2
Dennatoiogy
helped by prescription of Atarax and a topical steroid cream after the Kwell treatment to relieve
the pruritus while the dead epidermal parasites are being exfoliated. Kwell if jffliBO lljtectiViBlfei"
the crab lice infestations which are a rather common shipboard entity.
Dermatophytosis
Fungus infections are die next most often misdiagnosed or ill-managed dermatological
disease, A simple KOH Prep must be performed for every suspected case of dermatophytosis
before commitment to treatment. There are too many other diseases that can clinically appear
exactly like a fungus infection, and many fungal infections can present in nontypical fashion.
Aboard ship, two antifungal agents should be sufficient. Tliere is an all-purgose topical fungicide
available through the federal stoelc system that is usually effective against all forms of fungus
including true tinea, monilia, and tinea versicolor, This fungicide (two percent miconozole
nitrate) is ' available in either 85^am tubes by Ortho under the label of Monistat, or in
one-ounce tubes by Johnson and Johnson under the label of Micatin cream. This should reduce
or eliminate the need for stocking Tinactin, Mycostatin, Fungizone, Vioform, Mycolog,
Halotex, or Desenex. Seisun shampoo should also be used in conjunction with the Moni^tat or
Micatin in tinea versicolor, stressing hygiene and keeping dry. In true Hoeit ftftf&etiqp^, iiA4c4^^f#i
be easily distinguished from monilia or tinea versicolor with a KOH Prep, G4ao{wlyin (500 mgm
b.i.d. with meals) is effective, especially if lesions are located in hairy areas, nails, or in
granulomatous reactions. The treatment of any toenail fungal infection should be referred to a
dermatologist because results are frequently disappointing.
Pyoderma
Another complication of the humid environmmt is pyoderma. Impetigo is usually caused by
|3-hemolytic streptococci and is frequently associated with Staphylococcus aureus. It needs
systemic treatmentv a drug ©f choice is erythromycin, one gram daily for ten days in
conjunction with pHisoHex soap and topical bacitracin-neomycin cream.
Acne
Acne is frequently aggravated by the ship's environment. A follicuUtis-like acne condition
may be seen on the thighs, buttocks, and arms of a patient who works in an oil-contaminated
area; especially noxious are the halogenated hydrocarlwjns in machine shops, etc. A tropical-like
acne frequentiy develops on the trunk due to #ie macerating effect of continuously wet
clothing. Each case should be individualized but most need a b^yl peroxide topical peeling
agent such as Desquamex H.S., frequent washing with Fostex soap, shampooing each evening
with a nonprotein shampoo, and oral tetracycline. If deep papules or cysts exist, the patient wUl
need long-term tetracycline treatment of 250 mgm, one hour a.c, two to four times daily.
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U.S. Navd Pli^t Surgeon's Manual
Initially, there may be an irritating effect with the above treatment, followed by slow
improvemait, oftea reij«iri«g a mov^i to six weeks to see obvious dianges. If the condition is
very bad, the patient should be removed from the hot, humid, or greasy areas. Occasionally, a
keloidal acne occurs on the sternal, scalp, or nape area of Black persons. These lesions will
require intralesional injections of Kenalog (5 mg/cc) with systemic tetracycline and cautious
hygiene. On rare occasions a Gram-negative rod infection will develop in an acne patient on
long-terhi ltetfacyeline. TWs is easily identified by the clinical appearance of multiple superficial
pusttilei cdticentnifed itt the middle tWrd of the face. Except for this rare complication, all acne
patients should be considered noninfectious, and no waivers prohibiting haircut or mess cooking
should be considered.
Additional Common Dermatolf^eal Diseases
In addition to the diseases discussed previously, the following conditions are tliose most
commonly seen.
PseudofoUiculitis barbae (pfb) is an inherent problem associated with Black males who
shave. The razor produces a sharpened tip on the Mriky beard hair, making ingrowing within the
hair sheath or reentry into thi& skin possftle. The intruding hair acts as a foreign body and an
infectious or granulomatous cojidition develops. Legally, Navy personnel are allowed to ^ow a
neatly trimmed beard. If the beard is too scanty to appear neat, the use of depilatators should
keep the patient relatively asymptomatic. All Black sailors can be referred to the March 1976
issue of Ebony for an excellent explanation of pfb. Black marines may be forced to keep a
clean-shaven appearance. The use of depilatators is advised; under certain conditions a waiver
may be granted until the patient can be evaluated by a dermatologist.
Warts, especially plantar warts, are ubiquitous in healthy sailors. Corpsmen can be taught to
treat plantar warts with weekly paring and appUcatlon of trichloroacetic acid and 40 percent
salicylic plasters. Other warts can be treated with electrocautery, Cantharone, or hquid nitrogen.
PodophyUin (20 percent in tincture of benzoin) should be reserved for venereal warts in
uneircumdzed sailors and on the perirectal area.
Dandruff or seborrheic dermatitis can flare under the stress of a cruise and usually presents
no problem for diagnosis. A tar shampoo such as Sebutone and a steroid lotion such as
,01, percent Synalar oan be used. The same medications can be applied to the scalp of psoriatic
pattenfe along with topical Aristocort preparation for the skin lesions.
Acutely inflammed dermatological conditions which are manifested by erythematous,
edematous, oozing vesicles or pustules should be treated with Burow's compresses until the
10-4
Dermatology
lesions begin to dry. This would include pyodermas or infected lesions as well as allergic or
inflammatory diseases. Usually one Burow's tablet in one quart of tepid tap water, for use as a
compress to the dry area for 15 miniites t.i*d., will suffice. Once a lesion becomes dry, soaks or
compresses should heteduced and a^mpiiate cream or ointment continued or initiated.
Itifferpitial Diagnosis-Treatment Guide
The following diagnostic guide is suggested for use by the corpsman in sick call. It should
help diagnose and treat about 95 percent of the dermatology complaints.
Jock Itch
Differential Diagnosis:
tinea cruris positive KOH Prep
monilia positive KOH Prep
contact dermatitis history of irritant soap use or medica-
tion
venereal warts , . . . . viral; contagious venereally
moUuscum contagiosum viral; contagious venereaUy
herpes simplex viral; contagious venereally
scabies positive scabies prep; contagious
venereally
crab lice . . ^ . contagious venereally
erythrasma Corynebacterium; positive fluo-
rescence with Wood's light; non-
contagious; associated with poor
hygiene
Treatment:
tinea cruris, monilia keep dry; Miconazole or Grifulvin
venereal w*rts»
molluscum contagiosum podophyllin, liquid nitrogen, cautery
herpes simplex Burow's compresses, topical steroid
and antibiotic combination
scabies, lice . Kwell
erythrasma topical neomycin powder, erythro-
mycin
all others steroid cream, I.M. steroids if severe
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U.S. Naval FKght Surgeon's Manual
Athlete's Foot
Differential Diagnosis:
tinea pedis positive KOH Prep; frequently uni-
lateral
bacteria] infection macerated toe webs, pustules
eczema. frequently symmetrical, pruritic;
familial
dyshidrosis blisters, pustules; chronic
contact dermatitis blisters, pruritic, frequently sym-
metrical
neurodermatitis scaly; chronic
Treatment:
tinea pedis keep dry; cotton socks; powders;
Miconazole or Grifulvin
bacterial infection keep dry ; powder ; erythromycin
eczema, dyshidrosis,
contact dermatitis,
neurodermatitis steroid cream, I.M. steroids if severe
Itching
Differential Diagnoas:
urticaria positive history, lesions moving
around within 24 hours
drug eruption positive history
neuroses positive history, parasite phobia,
psychosis
soap contact dermatitis history of deodorant soap use
scabies positive scraping
miliaria rubra heat rash, especially in covered areas
or body folds
erythema multiforme ......... stationary, annular lesions
106
Dermatology
Treatment:
urtiearia keep cool; Atarax; epinephrine:
topical or, if severe, systemic steroids
drug eruption same as above; eliminate drug
neuroses MMPI; Thorazine
soap contact dermatitis discontinue soap and hot water;
topical steroids; Atarax
scabies , . . Kwell
miliaria rubra remove patient from hot, humid area;
clean, dry, soft cotton clothes;
Atarax
erythema multiforme refer to medical officer for worlmp
Papular Sqaamcius Lesions
Differential Diagnosis:
tinea. . positive KOH Prep; annular, non-
symmetrical lesions which enlarge
tinea versicolor poative KOH Rrep; lesions on trunk;
sweaty, oily skin, worse in summer
pityriasis rosea . .
seborrheic dermatitis .
secondary syphilis . .
eczema, neurodermatitis
psoriasis
. symmetrical lesions, not on face or
hands
. lesions in the nasolabial, sternal,
axilla, pubic, and scalp areas
. positive VDRL; frequently plant£tr or
palmar lesions; alopecia
. itching
, elbows, knees, and scalp frequently
involved; chronic
contact dermatitis,
dermatitis medicamentosa positive history
lichen planus lesions on penis, mouth, wrist, and
ankles; purple color; pmritie
lupus erythematoses. ......... lesions on sun-exposed areas, espe-
cially the face, leaving atropic scars
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U.S. Naval FK^t Surgeon's Manual
Treatment
tinea keep dry; Miconazole or Grifiilvin
pityriasis rosea Atarax; topical steroids
tinea versicolor Miconazole; keep dry; SelsUn
seborrheic dermatitis, eczema,
contact dermatitis, neurodermatitis,
lichen planus topical or systemic steroids
lupus erythematoses. topical or systemic steroids; sun
screens; a biopsy is indicated; refer to
medical officer
psoriasis tars; topical steroids; avoid systemic
steroids ' '
dermatitis medicamentosa stop causative drug; systemic steroids,
antihistamines, epinephrine
secondary syphilis see chapter 11 on venereal disease
Blisters
Differential Diagnosis:
herpes simplex . ........... on lips or genitalia; recurrent
herpes zoster , linear; unilateral; painful
varicella .............. generalized; febrile; positive history
tinea positive KOH Prep
contact dermatitis pruritic; positive patch test
impetigo .............. positive culture; positive Gram stain
drug eruption erythema multiforme; possible
history of drug ingestion
dermatitis herpetiformis symmetrical lesions with excoria-
tions; chronic
Treatment:
herpes simplex, herpes zoster cool Burow's compresses; Atarax,
Tylenol
varicella isolate; Atarax, Tylenol; compresses
contact dermatitis Burow's compresses; steroids (topical
or systemic); Atarax
10-8
Dennatologjr
drug eruption ctiscontinue drug; epinephrine; ± sys-
temic steroids; Atarax
tinea . , Miconazole or Grifulvin
impetigo pHiso Hex; topical neomycin; erythro-
mycin (systemic)
dermatitis herpetiformis biopsy ; refer to medical officer
Pyodermas
Differential Diagnosis:
acne ^ . . oily skin; not infectious
follicuKtis, superficial; in sweaty areas: non-
contagious
impetigo po^tlve culture; positivfe Gram stain
for strep, staph; contagious
pseudofoIUculitis barbae . Blacks who shave
furuncles, carbuncles deep; painful
cellulitis, erysipelas unilateral; red, hot, swelling, painful;
febrile; positive culture
Treatment:
acne tetrfteydine; benzyl peroxide; Fdstex
shampoo
folliculitis keep dry; dean, loose dry, cotton
dothes
impi^Q .............. etythrorttydn; pHisoHex; neomydn
pseudof oUicuIitis barbae no-shave diit
furuncles, carbuncles erthyromycin; hot soaks; pHisoHex;
I& D
cellulitis, erysipelas . refer to medical officer, admit to
ward; I & D ; systemic antibiotics
Hair Loss
Differential Diagnosis:
tinea. annular, scaly lesions; broken hairs;
positive KOH Prep
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U.S. Naval Fli^t Surgeon's Manual
seeoudaiy syphilis positive VDRL; patchy loss
alopecia areata annular; no scalp changes
scar history of trauma or previous scalp
diseases
male pattern baldness familial history ; hair root tip is white
breakage of hair shaft usually in Blacks
Treatment:
tinea. Grifulvin
secondary syphilis penicillin; notify PMU
alopecia areata intralesional Kenalog (5 m^cc)
scar intralesional Kenalog if keloidfi"
male pattern baldness no treatment
breakage of hair shaft discontinue use of hair straighteners,
hot comb, hair pic, excessive brush-
ing, alkaline shampoos, traction
(corn-row)
Dermatology Medications
Dermatology preparations or medications are predictably redundant and obsolete aboard a
carrier. Many of the antifungal agents are similar and ineffective. An excellent product for a
earner's pharmacy to stock is Aristocort cream (Lederle). "niis can be readily made into a cream
or oiplailfllt with variable strengths. Creams are most often used for the acute inflammatory
lesion, and an ointment is best for the chronic scaly dermatoses. Ointments should generally be
avoided in the hot, humid climates which prevail in many of the ship's spaces. Occasionally, a
steroid solution or lotion may be indicated for a hairy body region (Syntex's 20 cc,
0.01 p^cent Synalar solution)! A steroid spray may be indicated for first or second degree
bums or {iUhfopbd bites; 90-gram cans of Vdisone, Deca, or Kenalog spray are recommended.
Occasionally an intraoral medication is indicated such as Kenalog in Orabase (five-p-am unit). If
a parenteral steroid is indicated, and if the condition requires more than two weeks of
treatment, prednisone should be avoided in favor of I.M. administration with either multidose
Kenalog {40mg/cc), 5cc vial (Squibb), or 5cc vials of Celestone (Schering). Because of its
insolubility, a single injection of Kenalog wfll often satisfy a patient's need for a month. There is
usually a ^-hour delay before the drug is initially effective. A similar quantity of Celestone will
react initially in a few hours and will hold the patient for approximately three weeks. The
equivalent dosage of oral prednisone needed for similar clinical response will be in the
1040
Dennatology
30 mg/day range and would risk more adrenal suppression, even with single, daily doses. If a
parenteral steroid is chosen, the intramuscular route is preferred, since it assures dosage control.
The steroid should be given deep intramuscularly (hip) with at least a IV4" needle, as
subcutaneous atrophy has occurred from superficial injections. The parenteral Kenalog, diluted
with xylocaine to 5 mg/cc, can be injected intralesionally into keloids, into thick patches of
neurodermatitis, psoriasis, etc., or into areas of alopecia areata.
Mycolog cream is not recommended for frequent use. Its combination of steroid,
antimonilial, and antibacterial agents requires many stabilizers and preservatives which can
potentially produce a contact allergy. A pharmacy technician should be able to combine any
two or three active ingredienfa as needed and be able to avoid the over-dispenang of this very
expensive cream. The following preparations should be considered sensitizers, of uncertain
effectiveness, or uru-easonably costly: Mycostatin ointment, Tetracaine ointment, Eurax cream,
Furacin ointment, Desenex solution and ointment, Castellani's paint, and Vioform-
Hydrocortisone cream. Tacaryl or Tenaril are ineffective for itching; topieals and Atarax p.O. are
preferable. It is better to become familiar with a few drugs and methods of treatment than to
attempt the use of many.
10-11
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eaAFHRii
VENEREAL DISEASE
Introduction
Gonorrhea
Nonspecific Urethritis
Syphilis
Minor Venereal Diseases - -
Other Venereally Transmitted Diseases
Reference . .
Bibuography
Venereal diseases are defined as infectious diseases of man that are usually trflnsi|Uttejii by,
sexual intercourse.
There are many reasons for the recent increased incidence of venereal disease infections.
They are associated with changes in the organisms, the environment, and the host. There is
evidence that the organisms have altered virulence in some cases and altered antibiotic
Chemother apeutic sensitivity in others. Changes in the environment include demographic factors
and increased population mobility. The changes in the human host are improved nutrition and
hygiene, chariges in attitudes and behavior, and cJjsytiges; in aeJtya^ n .
At present, the teaching of venereal disease control occupies little of the curricula in medical
schools. There has been a shift of patients with venereal disease from the university hospitals
and federally supported treatment centers to the practicing physician. Medical sdw^gfft^Wlites
are frequently unprepared to diagnoiie and treat venereal disease. It is essential that shipboard
and field medical officers have appropriate references for the diagnosis, treatment, and control
of venereal disease. They should utilize their Sanitation Officer as a contact interviewer and to
complete the appropriate forms.
. ' ■ ...
This chapter is not intended to repkee the needf or BXJBipCf instructions or standard texts.
The recommended treatment choices and schedules will continue to change, and, wUI con^tpitly,
need updating.
11-1
U.S. Naval Flight Surgeon's Manual
Gonorrhea
The most commonly seen of the venereally transmitted diseases, gonorrhea presents
misleading national statistics. Approximately 80 percent of all gonorrhea is seen by the private
physician with only one out of nine of those cases being reported. There has been a continuous
trend since 1958 of an approximate ten percent increase in the rate of infection each year, with
a concommitant gradual increase in the reastance of the gonococcus to antiMotics.
The single injection or brief oral course that once made gonorrhea simple to cure is no
longer as effective. The problem is particularly severe in the Far East, but it is also being
reported far more frequently on the West Coast of the United States. Gonococci that are
relatively resistant to peniciUin are usually relatively resistant to other drugs.
EpidemiologicaUy, gonorrhea is an uncontroUahle disease for two major reasons. First, 75 to
90 percent of women who have gonorrhea are asymptomatic carriers. Second, ehnical diagnosis
is difficult in women. Unfortunately, the best laboratory test, the Thayer-Martin culture
technique, probably is not sensitive enough to diagnose all cases of asymptomatic infection. In
most studies on female contacts of infected males, only 50 to 70 percent of the females show
positive cultures.
Gonorrhea is a ubiquitous disease, and an attack confers no immuiuty to reinfection. In
fact, the phenomenon of reinfection or re-exposure after treatment has been dubbed
"ping-pong" gonorrhea. Transmissions via toilet seats, bath towels, drinking glasses, etc., are but
face-saving myths.
Neisseria gonorrhoeae is a bean-shaped, Gram-ttegative diplocoecus with the concave sides
adjacent. It is aerobic but grows best with carbon dioxide stimulus. It needs an akaline pH of
7.2 to 7.6, a temperature range of 35 to 36°, and moisture. It will grow only on columnar or
transitional epithelium of man.
^mptoms can occur as early as one day or as late as two weeks following sexual contact,
and the average incubation period for males is three to five days. In the female it is extremely
difficult to know when symptoms first begin. The diagnosis of acute gonorrhea in the male
usually presents no problem. The earliest symptoms of urinary discomfort and frequency of
urination are usually followed in a matter of hours by a purulent urethral discharge. If the
infection is allowed to continue for two weeks or more, it spreads backwards toward the
posterior urethra, prosbite, seminal vesicles, and vas to the epididymis. Proctitis, when it occurs
in males, is almost always a result of homosexual contact.
11-2
Yenereal DiseaBe
Gonorrheal complications may occur with or without prior symptoms of genital gonorrhea.
Gonorrheal arthritis, which occurs in three percent of untreated patients, may be accompanied
by tenosynovitis, particularly of the wrists or dorsa of the hands. Gonococcemia can produce
vesicular, pustular, petechial, or purpuric eruptions on th& extremities and may accompany joint
symptoms. Severe malaise, hyperpyrexia, and tachycardia may result.
The microscopic demonstration of Gram-negative, intracellular diplococci on a smear of the
exudate is adequate for diagnosis of gonorrhea in the male. However, very early in the course of
the disease and in old, untreated cases, the organism may be seen only extracellularly.
The recent reports of a significant percentage of asympto^fitic males, rectal and pharyngeal
gonorrhea in homosexuals, and the need to test for cure, necessitate that specimens for culture
be obtained. Peizer, Thayer-Martin, and Martin-Lester media are selective for Neisseria. A
negative culture one week after completion of treatment is practical; another culture two weeks
posttreatment is considered ideal.
Rectal and chronic genitourinary infectionB are generally believed more diMeult to eradicate
than uro^nital or acute infections. Penicillin has been the drug of choice for over 25 years and
remains the standard treatment. The latest recommendation for treatment of gonorrhea in males
is procaine penicillin, 4.8 million units I.M., divided into at least two doses and injected at
different sites at one visit. These should be accompanied by a one-gram dose of oral
probenecid. PenidlEn with two percent aluminum monostearate, benzathine penicillin, or oral
penicillin should not be used.
Since two to ten percent of all patients who receive penicillin have an allergic reaction, and
because of the emergence of penicillin-resistant strains from the Far East, alternate treatments
must be considered.
Tettacydine hydiroclilorijde--p^.- is Teeommended for the -patient who is aHergie-te-peniffiBElin,
procaine, or probenecid — l.Sgm initially p.o., followed by 0.5 gm q.i.d. for four days. The
longer-acting semisynthetic tetracyclines are easily absorbed and require fewer capsules but are
actually no more effective than tetracycline hydrochloride if given properly. AH tetracyclines
are ineffective as single-dose therapy.
The other alternate drug, spectinomycin hydrochloride, 2.0 gm LM. in one injection, may
be utilized but should be reserved for true treatment failure. Spectinomycin-resistant strains of
gonococcus have begun to appear, and indiscriminate use could lead to resistance to the one
drug now effective against the newer strains of peniciUin- and tetracychne-resistant gonococcus.
11-3
U.S. Naval flight Sui^eon's Manual
The proposed treatment schedule of gonorrhea with peniciUin or tetracycline will abort
incubating or concurrent syphilis, but spectinomycin has no effect on syphilis. Most cases of
recurrent symptoms after adequate penicillin or tetracycline therapy are not faue treatment
fiMmm; hut are more likely due to reinfection, nonsp^fic ureth]^#, or pos^onocoi^al
urethritis and should be treated as such.
Nongonococcal or postgonococcal urethritis is best treated with 0.5 gm tetracycline p.o.
q.i.d. for seven days. Eesistant or persistant &me& of postgonoiidccift^iireiimlis dhould be
continued for up to 21 days.
A person with known recent exposure to gonorrhea should receive the same treatment as
one known to have gonorrhea. There has been recent evidence of nonsymptomatic uretliril
gonococcal infiecfion in such men.
Pharyngeal gonococcal infections may be more difficult to treat than anogenital gonorrhea.
Posttreatment cultures are essential. AmpiciUin and spectinomycin are ineffective. Patients who
are still symptomatic or with positive cultures after 4,8 miUion urdlB of APPG phis one gram
prdBettedd should be given the 9.5 gm dosage schedule for tetracycline.
All patients with gonorrhea should have a serologic test for syphilis at the time of diagnosis.
Seronegative patients without clinical signs of syphilis who are receiving the recommended
parenteral penicillin schedule need not have follow-up serolo^c tests for i^hifis. PatieRts
treated with ampicillin, spectinomycin, or tetracycline should have a follow-up s^ologieal teat
after three months to detect inadequately treated syphilis. Patients with gonorrhea who also
h«ve syphilis should be given additional treatment appropriate to the stage of the syphilis.
Treatment for ^seminated gonococcal infection or the arihritis-dennatitis syndrome is ten
mduon units I.V. p^ day of aqueous crystalline penicillin G for three days or until there Is
8%nificant clinical improvement. This may be followed with ampicillin, 500 mgm q.i.d. p.o. to
complete seven days of antibiotic therapy. For penicillin or probenecid allergic patients,
tetracycline 1.5 gm p.o., followed by 0.5 gm q.i.d. p.o. to complete seven days. Additionally,
hospitalization is indicated for patients who are unifdiable, have uncertain diagnosis, or puridmt
joint isffusions or otiier eompHcations. Immobilization of the affected jointjis) appears
beneHeiid« Meningitis and endocarditis re^^e at least ten million ulute I.V. per day of
penicillin G for ten days or longer and up to a month for endocarditis.
Nonspecific UrelhiitiB
Few statistics are available, hut expeiietace suggests #at in many communities nonspe^c
luei&iitis PSU) is the commonest of the sexudly communicable diseases. There are many
Yenereal Eliseaee
causes of infection of the lower urogenital tract other than gonococcus. The nongonococcal
group of infections includes a number of cases in which the cause is known either because a
specific pathogenic organism can be identified or because the origin of the condition is
indicated by associated cHpieal findingB. ■ • ,j
Search for the cause of nonspecific urethritis has revealed at least eight different cauiative
factors:
1. Bacterial — staphyloeoeei, diptheroid ^
2. Trie-agent — trachoma (inclusion conjunctivitis), a member of Ihe bedsonia or
chlamydia virus group which includes the cause of lymphogranuloma venereum '
3. Mycoplasma (PPLO) — Certain other intracellular "t" forms have been implicated.'
4. Trichomonas Vaginalis
5. Mycotic Infections — Candida sJbicte, usually associjtfed willi urelhral trauma or
co-existing ^Habetes melBtus
6. Haemophilus Va^alis —■ Gram-negative, nonmotite, nonencapsulated, pleomorphic rod
but may belong to genus Corynebacterium
7. Allergy
8. Othera, mch. as tihetiiical, trauma, neoplasm.
5
Clinically, nonspecific urethritis usually presents with mild urethritis, scanty or moderate
mucopurulent urethral discharge, and variable dysuria. However^ it is occasionally clinically
indistinguishable from gonorrhea. The diagnosis is seldom in doubt if (1) the patient gives Ae
typical history of the onset of dysuria or urethral discharge 8 to 14 days or more after
intercourse with someone other than the regular sexual partner; (2) the gonococcus or other
likely cause cannot be found microscopically or in culture; or (3) the patient fails to respond to
the penicillin treatment schedule,
r .
The syndrome of NSTJ together with. nonsupportive polyarthritis is usually called Reiter's
disease and usually occurs as a complication of venereaUy transmitted, nongonococcal urethritis.
Anterior uveitis and ankylosing spondylitis are also reported complications of NSU. !'
NSU does nOt respond to penicillin. Tetracycline by mouth seems to be the most effective
treatment. Dosage sdiedules ran^ from one to two grants in four divided daily doses for; ofleto
three weeks. After eompletion of therapy, observation should be maintained for thtee months
by regular eswi&atiQit JE»f urine or urethral discharge. Serologic tests for syphilis should l^done
before treatment and at the end of three months.
11-5
U.S. Naval Fli^t Surgeon's Manual
Syphilis
Since 1970, there has been a slow but sustained increase in the number of reported cases of
syphilis, and it has become the third most commonly reported infectious disease in the United
States. Since the average physician sees less than one case of infectious syphilis annually, he
tasst maintain both a high degree of suspicion and a ^eat ffuniliaiity with &e viaried
ismitffestations of syphilis in order to make an appropriate diagtroaifc '
Treponema pallidum, the causative organism, is a very fragile and delicate spirochete which
dies quickly upon drying. It appears under the darkfield microscope as a corkscrew organism
6 to 14 microns in length, with 8 to 14 rigid spirals rotating on its long axis with a shght
bendini; and tvdsting motion.
Primary syphilis develops at the site ot direct contact with infectious lesions following an
incubation period of anywhere from 10 to 90 days (average 21 days). The primary lesion or
chancre begins as an indurated papule which rapidly breaks down to form a single, relatively
painless, clean-based, indurated ulcer. Transmission in the adult is exclusively by sexual contact,
m<i it is a systemic disease from the oiiset — indeed, before flie earliest signs appear. The
so-ealled typical lesion may vary from a sli^t erosion tp a deep ulcer but never has been
observed to be a bulla. Lesions can be multiple. The chancre is usually accompanied by bilateral,
discrete, painless, inguinal adenopathy after approximately one week, sometimes accompained
by generalized systemic signs of pharyngitis and malaise. Even without treatment, the chancre
heals in one to six weeks. Forty to sixty percent of males and ninety percent of females
djognosed with extragenital lesions do not recall their primary lesions because they were
pffljaless, hidden, or so inconspicuous that they were ignored.
Not all genital lesions are chancres. A host of diseases need to be considered in the
differential diagnosis, some of which are also venereaUy transmitted. The differential diagnosis
of primary syphilis must consider the following: chancroid, granuloma inguinale,
lymphogranuloma venereum, herpes, aphthosis, warts, scabies, trauma, drug eruptions, eancer,
psoriasis, and lichen planus. If the lesion is extragenital with satelUte adenopathy, tuberculosis,
tularemia, herpes, and cat scratch fever must be considered.
To confirm the diagnosis, even an experienced dermatologist needs more than the clinical
morphology; laboratory tests are essential. In early syphilis, the darkfield examination and/or
geological teste are mandatoiy.
The darkfield examination is essential since ordy a small percentage •&§ patients with a
EyphUitic chancre will have a positive serological test when the lesion first appears. If the lesion
11-6
Venereal Disease
is allowed to persist without treatment, an increasing number of patients will develop positive
serology but could progress throu^ the entire primary stage with a negative VDRL, Therefore,
a negative VDEL in the presence of a suspicious lesion does mot ttile out Ike ^t^oMs of
primary sypliiUs. However, unless treatment has been previously initiated, all primary lesions
will have positive darkfields. The mouth and anal mucous membrane contmn comni<c^
saprophytic spirochetes as normal flora. These are often misinterpreted and result in fals^
positive darkfield exams. Herein lies the problem for the physician in the fleet, dispensary, or
small hospital. Although only an ordinary compound microscope equipped with a darkfield
condenser and a fuimel stop in the oil immersion objective is used, very few lidioratory
technicians are experienced enott^ to accurately^ p!repare ^ patient, set up the examination in
a completely dark room, and have the patience to ^end up to two hours looking for the
^ost-Uke illumination of T. paUidum. All laboratory technicians perform supervised darkfield
examinations during training, but, in most military hospitals, virtually all darkfield examinations
are done in dermatology departments, if available. While in port, a PMU, local health
department, dermatology clinic, or hospital laboratory service may be available for assistance.
Unless the laboratory techracian has had recent and continuous experience, the darkfi^d
examination request will receive no more thffla Kp service, especially if it is apparent to the
technician that the requesting physician does not undeif tand the test and orders a darkfield on
every genital lesion seen in sick call. It is highly recommended that every deploying physician
require his laboratory technician to have refresher exposure to this technique and to conduct
dry runs aboard ship prior to deployment.
, Approximately 70 pereetit of syphilis is diagnosed on the basis of blood tests. There are two
types of tests. The nontreponemal tests measure nonspecific antibodies (reagins), and the
treponemal tests identify specific antibodies against treponemes. The nontreponemal tests have
continued in use because they are very inexpensive, sensitive, useful in screening large numbers
of patients, and important for following the course of the ^sease. Quantitative tilrfes of resins
increase as the illness progresses and diminish following treatment. However, they are not
specific. The VDRL slide test is an example of the reagin flocculation reaction, can be easily
performed by a laboratory technician, and is widely used. Reagin titres are usually negative or
low early in primary syphilis. As the disease progresses, the titre increases, and by the onset of
secondary syphilis, nearly aU patients will have a titre near 1:32. If the patient remains
untreated, the titie will usually go abo^ 1:32 in secondary syphilis and fall slowly during latent
syphilis. In some untreated cases, the titre wiU return to negative; however, in most untceated
cases, the titre will remain positive at a low level for life (serofast).
A change in VDRL titre is more important than any single value. A reinfected patient may
show an increased VDRL titre as the only manifestation of the most recent infection. Following
11-7
U^. Naval Pli^t Surgeon's Manutd
adequate treatment for primary syphilis, most patients return to seronegative within 6 to
12 months. Most patients with adequate treatment of secondary syphilis return to negative
VDRL within 12 to 24 months; however, some remain serofast at a low titre for Ufe.
i "
A sin^e, positive, nontreponemal test does not Gonfirra the diagnosis of syphilis. A hi^
titre or m increasing titre (at least two dilutions) is usua% m indication of infectious syphilis,
but reagin may be present in the serum for several other reasons. The list of biologic false
positive (BFP) reactions has become shorter recently with the improvement or increased
specificity in the antigen used. At present, the most important cause of a BFP is heroin
addiction, and the reaction may remain positive for as long as a year after stopping drugs.
Heroin addicts are in a hi^-ri^ age group and social setting for syphilis, however, so it would
b&mWiee to assume that an addict's positive serology is a BFP. Other causes of BFP leprosy,
old age, coflagen vascular disease, and autoimmune diseases. An acute febrile illness or smallpox
vaccination may cause a transient VDRL titre which usually returns to negative within two to
six weeks,
■ To rule oiit co-existing typhilis, or M a positive VDRL is nc/t supported by historical,
clinical, or darkfield data, a test for specific treponemal antibodies is indicated. The treponemal
test of choice is the fluorescent treponemal antibody absorption (FTA-Abs) test. The FTA-Abs
is difficult to perform, expensive, and caimot be quantitated accurately. It is 99 percent
Specific, however, and becomes positive earlier in primary syphilis and remains positive longer in
latent syphilis than the VDRL, irrespective of treatment. There have been recent reports of false
ptoffltive FTA-Abs reactions in patients with abnormal or increased globulins and in a few
pr^ant women. The FTA-Abs will also be positive for the other treponemal diseases of bqel,
f aws, and pinta.
' • On the first sick call of all patients with suspicious primary syphUis, a VDRIj and darkfield
should be done; if the latter is negative, it should be repeated on three consecutive days. If the
VDRL is positive, a quantitative VDRL should he ordered. Local or systmnlc rnitibiotics dhoultd
be withheld; saline soaks are indicated if the lesion is open, weeping, or crusted. If the initial
¥DRL and three darkfields are negative, the VDRL should be repeated weekly for four weeks.
A nonreactive VDRL at that point in a patient who has not received treponemicidal drugs is
satisfactory evidence liial the lerion was not of early syphilis. If the VJiftL positive and the
larkfield is negative or not available, an FTA-Abs is indicated. However, the FTA-Abs is not
readily available in the fleet, and if darkfield capabiUties are alsO unavafflable, the presence of a
rising titre (at least two dilutions) or a significant (1:4) sustained titre in a patient with a
suspicious lesion, is sufficient evidence for beginning treatment.
11-8
Venereal Disease
The treatment of choice for infectious syphilis (primary, secondary, and early latent — less
than one year) is benzathine penicillin G, 2.4 million units I.M. or 1.2 million units in each
buttock at the same visit. If benzathine penicillin is inappropriate, 4.8 million total units of
aqueous procaine penicillin given as 600,000 units I.M. dtoly for eight eonsscuMve days is the
altemaliye. Of al penicillins are not recommended. Every effort should be made to d&iliniejAt
penicill^ Mm^ h&tme tshtwa^g oHier antibiotics. Pot patictits who we^'aUisiEgie tft'lhfe
penicillins, tetracycline hydroehloiMe should be^ven — f 00 mgm orally, q.i.d. one hour before
meals for 15 days, or erythromycin, 500 mgm q.i.d. p.o. for 15 days. All patients with
infectious syphilis should have quantitative VDRL tests 2, 4, 6, and 12 months after treatment.
This schedule is especially important in patients treated with antibiotics other than penicilHn.
Ti>eatment failure or reinfection may occur and will need re^eabnent. When (a) E^pai«^
syihptoms of sypfaiHs p@rsist or reoccar; (b) thete is a sustained fbttif old increase in '"f BEIj -titri;
or (c) an initially high titre VDRL fails to decrease fourfold within a year, retreatxnent should
be accomplished using the same schedule recommended for syphilis of more than one-yean:
duration. Only one retreatment course is indicated.
Without treatxnmt, patient enters the secondary stage approximately six weeks to bx
months (average six to eight weeks) following the onset of the primary lesion, which is most
often gone by this time. It is quite common for the secondary skin manifestations to appear
without a history of a primary lesion. The lesions of secondary syphilis are quite variable, but a
few generalizations can be made. Rarely, if ever, are the lesions vesicular or bullous. They ar^
bilaterd and symmetrical, nonpniritic macules and papules frequently occurring on tiie p&tinf
and soles, corners of the mouth, sides of the nostrils, and in the moist anogenital regions. The
miQitBt lesions are highly infectious. Black people frequently have distinctive facial lesions that
are coin-shaped, with clear centers and a raised, rolled, hyperpigmented border. Also present in
secondary syphilis may be a patchy, "moth-eaten" alopecia, painless erosions about or in the
mouth, and flat, wart-like exerescences in the anogenital region. The patient WJ^ frequently
exhibit evidence of systemic disease including generalized lymphadenopafliy, phai^ngi^
malaise, fever, arthralgia, subacute meningitis^ nephropathy, and hepatitis.
A patient given an antibiotic for another reason, but in insufficient dosage for treatment of
syphilis, may never show clinical symptoms of a primary and may possibly never exhibit
seoondioy syphilis sMii changes. f'tJurlheKmore, a patient who has had an untreated bout of
syphlUi, Off in whom treatment was delayed until late primary or secondary stage, may, upon
reinfection, skip the primary stage and show secondary lesions as the earliest manifestation of
the disease. The serology will be positive in 100 percent of the patients with secondary syphilis.
In the absence of treatment, the lesions of secondary sypW^ heal in approximately 4 to
12 weeks, and the patient enters the lateht stage without scarring, ehnical signs, or ^rmptoms.
11-9
U.S. Naval Flight Sn^eon's Manual
In altout 25 percent of the cases, the secondary rash tends to reoccur periodically for up to two
years after exposure. When in the relapse state of untreated syphilis, sexual transmission of the
disease also ceases. Latent syphUis is defined as the absence of clinical lesion, a negative
darkfield, and normal chest X-ray and cetehrospmal fluid. The only manifestations of tiiis phase
are positive serologies. Those patients with positive spinal fluids have asymptomatic neuro-
syphiUs. The latent stage is subdivided further into early latent or infectious syphilis, up to two
years of infection, and late latent or noninfectious and greater than two-year duration.
For purposes of treatment and epidemiology, the late latent stages are grouped together
with tiie late manifestations of syphilis which primarily involve the cardiovascular and central
nervous systems, althou^ no organ of the body is immune. Discussion of the late stages is
beyond the scope of tMs presentation, but many excellent descriptions are available in most
standard dermatology textbooks.
The treatment for late latent, cardiovascular, neurosyphilis, or late benign syphUis is
7.2 million total units of benzathine penicillin G, given 2.4 million units in one dose I.M. weekly
tim^ three weeks, or 600,000 units of aqueous procaine penicillin given daily for 15 con-
secutive days (total nine million units). In patients who are allergic to penicillin, tetracychne
hydfo chloride or erythromycyin orally 500 mgm q.i.d. for 30 days is recommended. There are
recent reports questioning the effectiveness of benzathine penicillin and erythromycin and
tetracycHnes in the treatment of neurosyphihs, and the use of aqueous procaine penicillin
remains the only well-established treatment schedule.
There are several general considerations regarding the immunology, follow-up, and
posttreatment phases of syphdis.
The rule of "'/4's". The hypothetical situation of four sailors having intercourse wiiii a
prostitute who has infectious syphUis will result in three of the four developing primary s^hiUs.
If none are treated, two wiU develop secondary syphflis. If all remain untreated, only one will
develop tertiary syphilis.
Ah contacts of syphilis patients of less than two-year duration should be investigated.
Patients who have been sexually exposed to infectious syphilis within the preceeding three
months should be treated as for early syphflis, altiiou^ every effort should be made to estabBsh
a diagnosis.
AH patients with early syphilis should return for repeat quantitative VDRL's at 3, 6, and
12 month intervals following treatment. Patients with syphilis of more than one-year duration
11-10
Venereal Disease
should also have a VDRL 24 months posttreatment. Careful, follow-up serological testing is
particularly important in patients treated with antibiotics other than penicillin. Examination of
cerebrospinal fluid should be done on the last follow-up visit after treatment with alternate
antibiotics.
All patiente wffih neurosypMis must be serologicaEy followed for at least three years with
cerebrospinal fluid examinations and physical examinations every six months.
Herxheimer reactions occur in infectious syphilis patients within 12 hours after
administration of treponemicidal agents. They consist of headache, malaise, fever, sweating,
chills, and possibly a tempotdry exacerbation of the existing syphilitic lesions. This is not an
allergic reaction; treatment should be continued and only aspirin is indicated. Symptoms last a
few hours and are thou^t to be due to the rapid release of antigenic materials from the lysed
treponemes.
Minor Venereal Diseases
Lymphogranuloma Venereum
Lymphogranuloma venereum (LGV) is a venereafly acquired, systemic disease whose
causative agent is a virus Bedsonia (Chlaniydia), closely related to that of psittacosis. It is seen
Worlcl-wide but is more common in the tropics. The incubation period is usually 5 to 21 days
but could be several months. The initial lesion is normaUy so insignificant and transitory that it
is usually not observed. Most cases present initially with an enlarged suppurating inguinal lymph
node 10 to 30 days after exposure. Characteristically, the lymph node is lobulated, eloBgatedy
and parallels the long axis of the groin fold. Spontaneous rupture and multiple tistuke can
occur. Occasionally in severe cases, symptoms of arthralgia, meningitis, and conjunctivitis may
occur. The late manifestations are unlikely to be found aboard ship, and details can be found in
any standard dermatology text.
The diagnosis of LGV can usually be estabUshed by the clinical finding, positive Frei (sldn
test), and a complement fixation reaction. A positive Frei skin test remains podtlv© for many
year^ and may be indcative of past disease. A negative Frei test, however, in patients with
lesions for three weeks or longer, is strong evidence against the diagnosis of LGV. The
complement fixation usually has a high titre in the active stages of the disease; Titres of 1:30 or
higher are considered diagnostic of a recent infection with one of the viruses of ijiC
psittacosis-lymphogranuloma vmereum group. The differential diagnosis includes cKancroid,
syphilis, pyogenic infection, and neoplastic dise^e.
11-11
U.S. Naval Surgeon's Manual
The treatment of choice is tetracycline, 500 mgm p.c, one hour a.c. q.i.d, for one week,
then 250 mgm q.i.d. for the next two weeks. Aspiration of buboes may be necessary, but they
should not be incised and drained or excised, since this could lead to persistant draining sinuses.
^tOiioties should be withheld until syphilis has been ruled out.
Chancroid (soft chancre) is an acute, localized, venereal, self-limiting, autoinmmlahie dliseiiE»
caused by Heniflfthilus ducreyi. It is more common in tropical countries. F^alee are Irequ^tly
asymptomatic carriers.
The incubation period is usually three to five days but can be one to ten days. It is
(^sracterleed by foulnsmeUing, painful, undermined, single or multiple genital ulcers, and
mtarged and suppurating lyinph nodes. TTie lesion begins as a vesicopustule which ulcerafes
early, varying in size, and covered with a necrotic, dirty-gFayish exudate. Multilde lesions may
develop rapidly by autoinoculating. The inguinal adenitis usually begins five to ei^t days after
the appearance of the genital lesion. Approximately 50 percent of the cases develop the typical
bubo which is usually unilateral, large, erythematous, and quite painful. If untreated, they
gradually enlarge, soften, fluctuate, and spontimeously suppurate, forming a large crater.
Clinical appearance is quite suggestive of the diagnosis, but laboratoiy condfbatlQn is
desirable. Syphilis has to be ruled out. Gram-stained smears of the genital ejoidate may reveal
the Ducrey bacillus in small clusters (school of fish) as a short, plump, Gram-negative,
rounded-end bacillus, and it is occasionally intracellular. Frequentiy, secondary bacterial
infections may interfere with the 6ram^9t£&ed smear, so care should be taken in obtaining the
spedmett firom the undermined edges of small lesions.
The drug of choice is Sulfisoxazole, one gram q.i.d. for 10 to 14 days. The treatment is
specific, and if the patient does not respond, another diagnosis must be made. The sulfonamides
do not mask syphilis, and a serology done at the time of diagnosis and repeated three months
po^eatiaenf is desh-ahle. If the patient is allergic to sulfonamide, tetracycline, 500 mgm q.i.d.
fjM" 10 to 14 days may be used. Buboes should not be incised, but when fbctuant, aspiration
may prevent spontaneous rupture. If marked phimosis is present, warm saline soaks are
{referred.
Granuloma Inguinale
Granuloma inguinale is a chronic, painless, granulomatous, ulcerative venereal disease caused
by the Gram-negative bacillus, Donovania granulomatis. Much more common in tropical
11-12
Venereal Disease
countries, the mode of transmission is not always sexual. There is a inarked predUection for the
Black race and considerable variation in Individual susceptibility.
The incubation period is thought to be 1 to 12 weeks. The initial lesion is a small vesicle',
papule, or nodule which becomes eroded, leaving a sharply margined, ^anulating ulcer. The
viem slowly enlarges and frequently develops a secondary infection. The lesion is usually on the
penis but may be anywhere on the perineum or buttocks. Usually jio lymph nodes are involved.
The diagnosis can only be established by the demonstration of the Donovan bodies. They
appear in the large macrophages in a crushed specimen taken frinn the deeper tissue. When
smeared and stained with Giemsa or Wright's stain, they appear typically as "closed, safely-pin"
bacilli.
ui.
The treatment of choice is tetracycline, 500 mgm q.i.d. for one week, followed by 250 mgm.
q.i.d. for two to three additional weeks or until aU activity has subsided. Treatment should not
be started until syphilis has been ruled out. ;
Other Venereally Transmitted Diseases
Herpes ^rogenitalis
Herpes progenitalis is a recurrent, self -limited herpetiform of the genitals caused by type 11
herpes virus hominis, and in most cases, it is venereally transmitted. In the dermatologist's
office, it is probably the most common venereal disease seen and one of the most frequently
misdiagnosed. The cliiiieal man^staiibns range from the primary infection with severe focal
and systemic aj^pfoms, to the localized, minor, troublesome, recurrent lesions. There hiwif
been a nutiAer of new and interesting reports in the Kterature regarding herpes virus and its
assodation with cancer, chronic cutaneous lesions, newborns, and certain immunologic defects.
This DNA virus is of two specific antigenic types. Type I causes herpes labialis and Type H
is ^sodated with herpes genitalis. The two antigenic types hiCve two separate, specific
antibodies. These are reported to have been found in 43 to 96 percent of the gghersfi
population. Four to seven days after the primary infection, there is a fourfold rise in
complement-fixing antibodies but no appreciable change in titre in the recurrent disease. If the
patient has had a previous type I herpes, the primary of the type 11 will have a milder course and
vice versa. Ninety percent of primary infections are reported to be subclinical. The primary
herpes progenitalis infection is venereally transmitted, but the recurrent sdiaeks result from vtefl
multiplication, precipitated hf a variety of stimuH, i.e., focal trauma, constitutional disease^
11-13
U. S. Naval Flight Stugeon^ Manual
fl^r, urologic infection, emotional tension, and <>th^ nfimuiiologjietll Tfiiiismifision may
frequently follow sexual contact with either a cmrentty aymptomatic partner or a subclinical
carrier.
Hie primaty infection of the male is dimcally rare but usually presents wifti urethritis,
urethral discharge, and painM clustered vesidds on an eiylbieinatous base of the p^ins. These
thin-walled vesicles become pimilent, form crusts, and itlc^^ with subsequent potential for
secondary infection and scarring. The primary infection is accompanied by regional, exquisitely
tender, bilateral adenopathy lasting two to three weeks, and fever, headache, anorexia, and
generalisied mddse.
Recurrent bouts of herpes genitalis run a much more beni^ cour% lasting seven to ten days.
They are preceeded by a localized prodromal sensation of burning or itching one to two days
before the grouped clear vesicles, one to five millimeters in diameter on an erythematous base,
appear. The number of clusters will always be approximately the area of the primary but not as
extensive. Usually the blisters erode or become cloudy and erode one to two days after onset,
leaving superficial ulcers which crust over and heal within seven to ten days unless complicated
by occlusive, macerating ointments or secondary infection. There may be regional adenopathy of
a lesser degree than in primary infection.
A simple diagnostic test for herpes genitalis is the demonstration of giant cells with multiple
nudear and acidophilic incKtaons in cytologic smears from the base and roof of vesicles that are
Stained with Wrist's stain. Herpes zoster/yarieella also prpdticea id«intical cytological finding,
but it is hardly a clinical d^a«ntiai* Tbfi dinical^ecentifil tfiagnosis includes syphilis chancre,
diancroid, and gonorrhea in &e pmna^ infection. With a history of recurrent blisters, other
more exotic diseases such as genital excoriations, Behcet's syndrome, erythema multiforme,
fixed drug reaction, and pyoderma should also be considered,
Tliere are no spedJic remedieg for d&er primaiy or recun«nt herpes. Many treatment
niodEdities have been and are currently recommended, but local cool saline or Burow's
compresses are the mainstays. An attempt should be made to determine some of the' posable
precipitating factors of the recurrent lesions.
Trichomonal Infections
The parasite Trichomonas vaginalis is a common cause of infection of the genitourinary
tract, is usually sexually transmitted, and catuses a uretihiitis and prostatitis in men. The true
incidence of the disease is unknown. It can be found in 12 to 15 percent of all men presenting
witii urethritis (Gatterall, 1972). This flagellate protozoan can be found in the male urethral
11-14
Venereal Disease
secretions, prostatic secretions, urine, and occasionally in the seminal fluid. In uncircumcised
men, it is frequently found in the subpreputial sac and can cause a balanoposthitis. Usually men
serve only as an asymptomatic carrier, transferring it from one woman to another sexually
without developing any symptoms or signs of the disease. The incidence of trichomonal
infections is quite high in sexually promiscuous females or prostitutes. The incubation period of
the disease is often difficult to determine, but most eommonly it is tiicwght tQ be A t®
After careful questioning, a male patient will admit to noticing itching and discomfort inside the
penis and a sUght moistness at the tip of the penis for a few days, disappearing spontaneously.
Occasionally some men will notice an early morning discharge. However, some will have a
purulent discharge, frequency, and dysuria resembUng gonorrhea or NSU. On physical
examination no abnormal physical findings s«& #ie mle, but some reveal a redness of like
external meatus. The first glass of a t^ro-glass uiine i^eeimen will firequently contain flueads and
flakes* The prostate is frequently infected. CystitiB, epididymitis, and urethral stricture ceflj
result from infection.
The diagnosis depends on demonsfrating the organism microscopically. In the male,
repeated examinations mi^ be ttiEscewary, tating an esetlf memtiiBg scraping of theiiMtua h^om
passing the morning urine. On the han^ng-drop preparation,' ite odgianiam wiH appear I® *©*
30 microns in size, globular, with an oval nucleus. It has four free flageUa at the anterior end
and one flagellum attached by an undulating membrane.
Other causes of urethritis in the male that must be excluded are NSU, gonorrhea, bacteiM?
urethritii due to E. coK o* lhemophilus» chemical urethritis, Candida urethritis, traumatte
urethritis or urethritis secondary to urethral condylomata, acuminata, chancre, shicturej
carcinoma, etc.
The treatment of trichomoniasis has been revolutionized by the introduction of
metronidazole in 1960. This narrow spectrum drug is specific for trichomcMiiasis, and, given
orally at g4osage of 200 mfm .tiA after meals for seven ^f#i4t is effeclaye in 80 percent of
the cases (CatteraU, 1972). If the regular sexual partner Is not tt«»ted, reinfeetigtt obviously is
quite common, and sexual intercoutse diould be prohibited during treatment. Metronidazole
has a slight antabuse effect and may produce unpleasant symptoms if alcohol is taken at the
same time as the tablets. Treatment failures are usually due to failure by the patient to take the
tablets, reinfection from the sexual partner, or failure to absorb the drug through tiife GI tract.
In these cases, retreatment with twice the initial dose is recommended.
11-15
U.S. Naval Fli^t Solon's Manual
Scabies
' Sarcoptes scaLiei var. hominis has played a modest but not insignificant role in history.
There are books describing its effects on an army's morale, sapping ihe strength of Hie men and
the initiative of their commanders.
^ Huinan scabies is world wide and ^ows cydical fluctuationa. There has been a world-wide
^idattfc of soabi^ mnm 1974*1975. Scabies is usually spread by «lose personal contact. The
mite can not survive more than a few days away from the skin. Either fertilized females or
nymphs may be transferred. The age group and seasonal influence of venereal disease coincides
with outbreaks of scabies, and promiscuity is the usual mode of spread, although military
ou'&reaks are common where berthing conditions are congested.
Scabies are microscopic, whitish, .2 x .2 mm, spiny, bristlyi ei^t4e^ed mites. The fertilized
female excavates about two miUimeters per day of burrow in stratum corneum, depositing
two to three eggs per day, for a total of 10 to 25 before dying in the burrow. The six-legged
larvae emerge from the egg in three to four days, wander to the skin surface and either reburrow
OT find new hosts. They then undergo three mote mcJults rdachiiag maturity 14 to 17 days after
eggis laid. At tliis. point, copulation occurs in the burrow with the female excavating and
kying and the male dying.
The mite favors certain areas of the skin, with the distribution of the mite population not
necessarily representing the site of initial infestation. In the adult male the most frequent sites
of/infestation are finger webs, elbowis, and glans penis. Any area can be involved, but the mites
rarely infest the chest or back and almost never involve the head.
r
Itching is the most obvious and intractable clinical manifestation of scabies, and in some
early cases, it may be the only manifestation. Itching is usually worse at night and may be
inteiisely severe. The onset of symptoms is usually noticed three weeks to three months after
infeistation, but earlier in subsequent or reinfestations. Apparently, allergic sett^tivftf ' to the
mkm md pioiaefe of the mite pkys an important I'ole in the development of the lesions and the
degree of pruritus. The so-called secondary lesions frequently dominate the clinical picture.
Large numbers of small, urticarial papules often develop on the abdomen, thighs, and buttocks.
Indurated inflammatory nodules resulting from prolonged scratching may persist for weeks or
months after tiie icabies hits been eiMeotively treated. Secondary infection, crusting, and
empefization frequently complicate the clinie^^cture.
The chnical picture can effectively estabUsh a diagnosis in most cases. A scraping of the
lesion examined under low power of the microscope witt prove the diagnosis when the mites,
11-16
Venereal Diseaae
ova, or feces are visuaEzed. Despite what seems an easy diagnosis to establish, scabies continues
to be one of the most frequently misdiagnosed dermatological conditiQm seen today. Many
cases are diagnosed as psoriasis, eczema, impetigo, urticaria, allergies, mi arthropod bites. ^
Ttet m aeveritl effective seabiecides available, but gamma benzene hexachloride (KweU)
remains a favorite. The patient must adhere strictly to the prescribed treatment routine. After a
hot bath, in which the skin is thoroughly scrubbed, Kwell must be applied carefully to all skin
below the neck. Kwell remains on the skin for 24 hours, and after another bath, all
underclothing and bed Hnen should be changed. The same routine ishould be repeated in four to
seven diys. ^eieis never a need for other applications, as overtreatmeirt can create irritatipn.
Frequently, the use of antibiotics, topical or systemic corticosteroids, or Atarax may ^ be
indicated in infected or heavy infestations. All itching members of the berthing area or work
center should be treated, even in the absence of obvious infection.
MoUuscum Contagiosum
Molluscum contagiosum is an exclusively human infectious disease caused by a pox virus.
The virus is common throu^out the worid and usually kvtllw cWlAfen but frecjuently is seen
in the genital pelvie am (af sejmdly active advdts. Inuiemission by direct cpntAM.ta WMSi^
but it is usually ^ffieult to trace. Frequently in children a Koebner or isomorphic restt^nse^^ii
noted.
The incubation period is variously estimated at 14 to 50 days. The individual lesion is a
shining, pearly-white, hemispherical, umbilicated papule which may show wCi$ntr^ ]^l)P^
be id^^ted wtb a hand lens when Is^ ^tjEoi one j^lteieter in diameter^ lidai^ing ^cSfrl;^,!^
iBi^ reat^ a dimeter of five to ten milBifte^es in 6 to 12 weeks. When found in the pelvic area
of an adult, usually only a few lesions are present. A solitary lesion may persist and become
quite large, resembling a pyogenic ^anuloma, epithehoma, or keratocanthoma. . .
The duration of the lesion is quite variable. When multiple- wd in raoit e«B(^#n eW3^
the leaalDn is self'limiting miMa sU to nine months. The large or solitary lesion may |S6
extremely pKEsistent, and eases have beeii sported to be pr^nt over four years. After trauma
or spontaneously, inflammatory i.cfean|e8 result in suppuration, crusting, and eventual
destruction of the lesion.
Direct microscopic examination lof flie' uoitmed cuiretted leaon (mifiMi'bffewein itwo
glides establishes the di^g^im with readily visualized, large (25 microns), viral ineluwonvbodfes.
H-17
U.S. Naval Plight Surgeon's Maaual
The choice of treatment will often be determined by the number and location of the lesions.
A smalt number of lesions may be easily removed by shaving with a scalpel or curettage under
local anesthesia. Patients should be re-examined every two weeks for two to three months to
insure irradication of previoudy inconspicuous lesions. When many lesions ace present,
20 percfe«t podophyllin in 95 percent alcohol may be applied weekly but often has to be
continued for many weeks.
Condylomata Acuminata
Also known as venereal warts, condylomata acuminata can occur around the
mucocutaneous junctions and intertriginous areas of the genitaha and" perianal region.
Condylomata acuminata, along with all other infectious warts, i.e., common, plantar, plane,
accuminate, etc., are caused by the same papovavirus parasitizing the epidermal cell. Hhe
histological and clinical variants are attribUfted to differences in host response, dependent on
site, immunity, and other factors.
Little is known about natural or acquired immimity to this virus. There is evidence of
widespread variation in susceptibflity to infection and in the duration of attacks, with some
individuals showing partial or complete immunity. It has been generally observed that extensive
warts of any variety that remain throu^ their natural course on children (average of two years)
will provide immunity in later life to any variety. There are frequent failures to find warts of
any type on the sexual partner of a patient with extensive condylomata acuminata.
The incubation period after experimental inoculation averages about four months (range
Ito 20 months). Perianal warts are frequenfly seen in male homosexuals, but the natural
history of venereal Warts is no less variable tiban that of other types. Marty disi^eio' after a few
months, especially when the moist condition which favored their development is reversed, but
others persist for many years.
i^e itidsniAml wart is soft, pink, elongated, sometimes filiform, and often pedunculated. In
soine patients, large cauliflower-Eke masses may form with malodorous changes resultii!^ from
accumulated fecal material, maceration, and bacterial actMty. OecasiOnally, flie Warte inay
invade the urethra with development of pain and serosanguinous discharge. The moist, wart-like
changes of secondary syphilis (condylomata latum) may be considered in the differential.
Venereal Warts in ihe moist non-keratmizing areas respond dramatically to local painting
with podophyllin. Fodophyllni resin, 20 percent in 95 percent alcohol, inhibits mitosis and causes
swelling and necrosis of'cells it can penetrate. The dry keratin mantie of dry warts or the center
of large vegetating masses may not respond to regular weekly paints and should be removed
11-18
Venereal Disease
with curettage and electrodesiccation. Special precautions should be taken in tiie treatmettt of
coronal, sulcal, or glans warts in an uncirCumcized patSeat, as swelluig irequefltly maM in
phitnoi and a dorsal spUt may be required. All patients shmild be instruGted to Boak or wash
the podophyllm off six hours or less after weekly tppliealioni
Pediculoffls Pulas
The pubic or crab louse, Phthirus pubis, is a dorso-ventrally flattened, wingless insect with
front legs strikingly crablike and is an obUgate parasite of mammals. Both sexes suck blood and
inject their saUva in the process. During the female's life span of about a month, she lays sevpn
to ten eggs each day. The eggs hatch in about eight days, and the nymphs re<juire a further ei^t
days to reach maturity. The eggs are oval, Hdded capsules, firmly cemented to the hair.
Pubic lice occur commonly throughout the world, and, although usuaUy found in pubic
hair, they can be found on the hairs of the abdomen and thighs. Rarely they may invade the
scalp, axillae, eyebrows, and eyelashes. Infestation is usually transmitted by sexual contact but
may be transferred by clothing or towels, and sometimes by shed haars. The site of
parasitization often indicates fte mode of transmission, for these Uce move only very short
distances from the point of first contact.
Intense itching or irritation is at first the only symptom, usually two to three weeks or
longer after initial contact. Later, a secondary infection and eczematization may occur. Heavy
infestations have been reported, associated with fever, malaise, headache, lymphadenopathy,
and a leukocytosis. Extreme senativity has resulted in bullous lesions.
The diagnosis could be overlooked in the presence of severe secondary infection, and the
Uce and eggs should be carefully sought, as they are readily visible to the naked eye.
AppUcation of Undane (gamma bettasene hexachloride), available under the tirade name of
KweU, is a highly effective ti-eatment. The cream, lotion, or shampoo is applied after bathing
and left on for 24 hours. The patient should then wash thoroughly again and put on freshly
laundered clothing and sheets. The same process is repeated four to seven days later.
Reference
Gatterall, RD. Venereal diseases. Medical Clinic* of North America, 1972, 56(5).
BiUiogra^y
Benenson, A.S. (Ed.). Control of commMi^U d&eaie« in man (11th ed.) (SBN: 87553-054^). Washington,
D.C.: Tlie American PubKc H«aldi Aaaodation, 1970.
11-19
U.S. Naval Fli^t Su^eon'a Manual
Department of the Navy, Bureau of Medicine and Surgery. Interviewer'a aid for venereal disease contact
iljfiW^tiens (NAVMED P-5036). Wariiinglon, D,C. Jm
Department of the Navy, Bureau of Medicine and Surgery. Manual of Ae medical department Article 22-18,
venereal disease control. Washington, D.C., August 1975.
Department of die Navy, Bureau of Medicine and Surgery. Treatment schedules for gonorrhea and sviMlis
(BUMED 6222). Washington, D.C., 8 September 1976.
Department of the Navy, Quef of Naval Operationfl. General military traiiiin£ pronram
(OPNAVINST 1500.22C). Washington, D.C., March 1975. -e r "e-
Department of the Navy, Office of the Secretary of the Navy. Policy of venereal disease control
(SECNAVpST 62^1), Washington, D.C., 20 November 1973.
Ymereal diseases. Medftad Qinict of North America, Septetnber 1972, 56.
Venereal disease. MEDCOM Learning Systems. New York: Pfizer Laboratory, tie, 1972.
11-20
12
5
o
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CHAPTER 12
DENTISTRY
The FUght Surgeon's Role in Aviation Dentistry
Odontalgia and Aerodontalgia
Oral Health '
Preventive Dentistry
Diagnostic Procedures
Dental Records and Terminology
Raferen^ces
Bibliogrqthy
The Flight Surgeoil's Role io Aerospace Dentistry
The field of aerospace dentistry requires a close working relationship between the FUght
Surgeon and the Dental Officer. This relationship is necessary because aerospace dentistry is
I ^ concerned with dental-medical ailments, as weU as with disorders which are of a distinctiy dental
nature. Dental treatments may have an adverse effect on the f^t^tatui of aviation personnel.
All but the m<Mt unusual Navy and Marine instaUationi to whidi flie FKght Surgeon n^t be
asdgued idtt delude personnel of tiie Dental Corps. Therefore, the FUght Surgeon need not
concern himself with emergency dental procedures. These considerations are the baas for
specifying the foUowing dental-medical related duties for the FUght Surgeon:
1. Medical Administiative Control - The FUght Surgeon's responsibUity for medical
administrative control of flight personnel requires that he know which persons are undergoing
dental treatment, the specific disorders being treated, the particulars of the tceatinent bein^
employed, and the effect of the treatiment on the individual's fitness for flying duty.
2. Diagnosis - The FUght Surgeon may be required to interact with the Dental Officer in the
differential diagnosis of medical disorders. In unusual circumstances where a Dental Officer is
not available, the FUght Surgeon may be caUed upon to diagnose and ar^iinge for the disposition
of emergency casfes of dental and dental-related disorders.
3. Dental Terminology in Records - For two reasons, the FUght Surgeon should have a
working famiUarity with the terminology in records involved in aerospace dentisty. First, the
interaction of the FUght Surgeon and the Dental Officer will be most effeetiare when the Fli^t
Sui^on has a knowledge of human dentition and associated terminol<^. Second, tiie Flight
12-1
U.S. Naral Flight Surgeon's Manual
Surgeon is responsible for establishing or veriiying the identity of deceased persons involved in
fatal aviation accidents.
Odontalgia and Aerodontalgia
Plainly stated, odontalgia is a toothache, and aerodontalgia is a toothache provoked by
lowered barometric pressure during and after actual or simulated flight.
The neurovascular component of a tooth, the dental pulp, is a deUcate connective tissue
interspersed with tiny blood vessels, lymphatics, and unmyeliuated netves. It reacts like other
body connective tissue to bacterial infection and other stimuli - i.e., an inflammatory response.
This response is called pulpitis and is primarily the result of dental caries in which bacterial
infection of the pulp occurs. Due to its anatomic features of hard dentinal wall and tiny apical
foramina, a t»oth is particularly vuhieraljle to inflammatory response. The hyperemic and
edematous phases of inflammation cannot be dispersed, and resultant increased pressure usually
causes necrosis of the pulp. CUnically, the symptoms may vary from an occasional dull,
throbbing pain of an intermittent nature to sharp, lancinating pain causing extreme discomfort
requiring immediate attention for relief. Other, less common causes of pulpitis are chemical
irritation from medication placed in or around a tooth during dental therapy, thermal irritation
%#B«»fftSf#0Bal .heat produced during treatment or'from large, metallic, uninsulated dental
rigiPSlionfl, and, trauma, varying from a mild blow to out^| fracture of a tootii.
A condition simulating pulpitis by the occurrence of odontalgia was reported by flying
personnel during World War II. It occurred more frequently during and after flights at higher
altitudes and was called aerodontalgia. It is relatively uncommon and is associated particularly
with recently filled tee& or teeth in which vascular or hyperemic changes in the pulp are
present. Burket (1946) found that aerodontalgia is a condition intimately related to pre-existing
dental pathology and usually represents an acute exacerbation of Subdinical eymptoms. Orban
and Ritchey (1945) stated that 1 changes in atmospheric pressure aggravate the impaired
circulation in irritated or diseased pulps and may lead to early manifestations of inflammatory
and degenerative changes in the pulpal and periapical tissues.
Sognnaes (1947) investigated radial acceleration as a possible fctviting factor in
aerodontalgia. Flyers with a high incidence of dental and periodontal disprd^]^ were subjected
to human centrifuge accelerations equal to and greater than those experienced in fli^t. These
experiments failed to reveal subjective symptoms referrable to the teeth.
It has been suggested that air entrapped under restorations may be a cause of aerodontalgia.
NiMnerous investigators have experimentally produced m bubbles under dental restorations and
12-2
Dentistiy
exposed the patients to low barometric pressure. No symptoms were experienced in these cases.
This evidence, as well as rational analysis, indiqates that trapped air under restorations is not a
likely cause of aerodontalgia.
Oral Health
The Flight Surgeon alone bears the ultimate responsibiUty for the overall health of the unit
to which he is attached. Oft^ overlooked is the obligation to insure adequate oral health as a
part of the physical fitness of aviators and other equadion personnel. Accordingly, it is essential
that he have rapport with the Dental Officer and the senior dental technician at all times and
seek dental treatment for those personnel who are his responsibility.
Many recruits and reservists coming to active duty are in poor dental health. They average
seven to eight carious leaons. During recruit training, approximately 25 percent of needed
dental treatment may be accomplished. Accordingly, many reach their squadrons in need of
further dental treatment. Each squadron, furthermore, has its floating population which avoids
dental treatment because of apprehension and lack of oral health education. The greatest
problem attendant to lack of dental treatment for deploying squadron personnel is insuring
their presence at the dental clinic with sufficient lead time to accomplish tite necessary
treatment prior to deployment. Advance planning on the part of Medical Depmtment
representatives would do much to overcome this hurdle.
Preventive Dentistry
Dental disease affects virtually 100 percent of military personnel. The two most common
disorders, dental caries and periodontal disease, are usually the result of neglect and lead to
needless discomfort, loss of productive time, and decreased unit ^ectiveness. Today, there is
sufficient knowledge of the nature and etiolo^ of oral \ disease, and there are adequate
techniques of prevention to ride out virtiiaBy aD new dental caries and periodontal disease.
eOHsequenfly, the Flight Surgeon should insure the participation of tile personnel for whom he
is responsible in the Preventive Dentistry Program conducted at all Navy and Marine Corps
installations having dental personnel. The FU^t Surgeon should be famiUar with the Bureau of
Medicine and Surgery Preventive Dentistry Manual (NAVMED 5087), the Preventive Dentistiy
R-ogram of the Navy or Marine Corps installation to which his unit is attached, and priority
preventive dentistry measures that should be accomplished prior to deployment of his unit.
The FUght Surgeon can assist the Dental Officer by insuring that personnel have the
following accomplished to tiie extent dental services permit:
1. Annual dento-oral examination (SECNAVINST 6600.1B) to assess the dentition,
periodontium and other oral tissues, and oral hygiene. The Flight Surgeon, as
12-3
U.S. Naval Eli^t Su^ori'a Manual
representative of his Commanding Officer, shall provide a monthly list of personnel for
examination to the dental activity responsible for their care. The list is compiled by
using the last digit of the individual's social security number in the following manner:
1 - January 6 - June
2 — February 7 — July
3 - March 8 - August
4 - April 9 - September
5 - May 0 October
2. An aimual dental prophylaxis to include:
a. removal of plaque, exogenous stains, and calculus from the teeth
b. application of an approved topical anticariogenic agent (three-agent stannous
fluoride treatment).
3. Preventive dentistry counseling to in^dufd patients and groups on:
a. effective tooth-brushing and oral soft tissue care at home
b. the use of approved dental disclosing agents dtu^ home care procedures
c. how to clean prostheses and maintain the supporting tissues in a healthy condition
d. itol^ -eonifeteney of food, frequency of eating, and food habits for proper nutrition
and dental health.
4. Construction of mouth^m^ds for partic^ante itt contact sports. Recipients of
mouthguards must be instructed concerning cleaning and maintenance procedures.
The FUght Surgeon should inspect tiie hard and soft tissues of the oral cavity as a matter of
routine in all physical examinations. Dental disease can then be detected in its incipient stage
when treatment is most effective.
Diagnostic Procedures
The Flight Surgeon may be called upon to participate with the Dental Officer in the
diagnosis of medical-dental ailments. Also, on rare occasions, it may be necessary for the Flight
Surgeon to diagnose and arrange for the disposition of distinctiy dental problems when a Dental
Officer is not readily avail^le. To assist the Ffi^t Sui^on and prepare him for these roles, this
section summarizes diagnostic procedures, first for cases of aerodontalgia, and tfien for
medical-dental disorders.
Diagnostic Procedures for Aerodontalgia
Orban and Ritchey (1945), on the basis of 250 cases of toothache of decompression origm,
recommended that the following diagnostic procedures be employed to assess aerodontalgia.
124
Dentistiy
Case History. Information should be obtained from the patient regarding history and
drcurastances surrounding occurrence of the problem as follows:
1. Previous unprovoked pain, especially at night
2. Previous hypersensitivity to heat, cold, sweeis, or pressure
3. Approximate age of restorations in the suspected area
4. Unusual pain durieg the operative treatment or during the following ni^t
5. Pain during ascent at descent. If on descent, it Aould include the lengii of ttoie spent
at maximum altitude.
6. Altitude at which pain oc^nrred and the length of time the pMent remained at that
level
7. Character of the pain: sharp or dull, dngle or intermittent, intense or mild
8. Altitude at which pain was relieved
9. If pain persisted after reaching ground level, the length of time it persisted and whether
it was followed by swelling in adjacent areas
10. Tooth or teeth suspected by the patient.
Roentgenograms of the suspected area or quadrant should be available.
Cttrd&a ExtmUismn, These guidelines should form the framework for diagnosing suspected
cases of aerodontidgia:
1. An estimate of the age of resloratioii in the suq)ecsted area
2. Percussion or pressufe test from the lingual and facial aspect as well as on the occlusal or
incisal edge of the involved tooth
3. Exploration f 01* carious lesions or defective restorations
4. Response to local application of ice, heat, and electricity
l^adiographic examination of the teeth and periodontium in involved areas
6'. Removal of restorations and curettement of cffldous lesions
7. Repeated decompression tests, if necessary.
An examination of this character should give information which can be interpreted
according to the following guidelines:
1 . Unprovoked pain, especially at night, wouM be a strong indication of pulp involvement,
probably of an acute nature.
12-5
U.S. Naval Flight Sunn's Manual
2. A tooth that has shown previous hypersensitivity should be carefully examined.
Sensitivity to heat and not to cold, or relief of pain by cold would suggest a tooth with a
nonvital pulp. Equal response to heat and cold indicates hypersensitivity (pulpitis). Prolonged
pain from cold points to pulp inflammation. Hypersensitivity to sweets tends to surest caries
or a defective restoration. Pain tin pressure mdicat^ periapical irritation but not necessarily
abscess formation. (Occlusal trauma should be eliminated.)
3. Amalgam restorations of recent dafeM We more suspect tfian old ones.
4. Unusual pain during treatment or during the night after the tooth was restored su^ests
pulp exposure or pulp irritation.
5. Pain during ascent indicates that the affected tooth has a vital pulp; pain during descent
indicates a tooth with nonvital pulp. There appears, however, to be a "lag" between the
irritation and the reqjonse, and thus a vit^ tooth mi^t hurt briefly during descent if a very
short time had been spent at maximum altitude.
6. The altitude at which the pain Qiraeura during ascent should give some indieation as to
the degree of inflammato^ process in tbe pulp. The lower the p^aspiWt sititude at which the
pain occurs, the more acute the inflammation.
7. at 43,000 feet (istandard prewre chamber altitude), after some time at high
altitudes, should focus attention on a tooth with a nonvital pulp.
8. Sharp pam during ascent would indicate a tooth with a vital pulp and with a rather
acute inflammation; dull pain during ascent would point to a chronicaUy inflamied pulp. Dull
pain during descent would indicate a tooth with a nonvital pulp or an inflamed maxillaiy sinus.
9. The sooner the pam is relieved during descent, flie more acute the inflammation is apt
to be.
10. Pain that perrists for a long pmod after ground level is reached is sometimes associated
with teeth with necrotic or nonvital pulps.
11. Usually, the patient has no difficult in pokting out the quadrant in which the pain
occurred, but his selection of the tootil within the quadrant has been found to be unreliabfe. It
is not unusual to have pain referred to the region of another tooth, espeei^y the mandibular
molars and bicuspids, when maxillary teeth are involved.
12. Roentgenograms are important in diagnosis, but they cannot be expected to disclose
pulp changes or minute exposures of the pulp, ' '
13. Observation should indicate the approximate age of restorations. Amalgam restorations
of recent date can usually be recognized. Older amalgams may reveal shiny spots indicating
12-6
Dentietty
poiffits #f excessive conttfet vfkem tWe teitotatioii is hi^, resulting in pu^al irritation and
14. Percussion and preissure tests are indicative of periapical irritation but not necessarily
abscess formation.
15. Carious lesions and defective restorations should be explored. The more open a lesion
and the more defective the margins of a. restoration, the less suspeGt is a tooth for having been
painful during decompression.
16. The best diagnostic aid has been the response to stimulation with ice. Nearly all teeth
with vital pulps will respond to this test, but it is necessary to differentiate between
hypersensitive teeth and those reacting with prolonged pain to irritation wititi ice. In
hypersensitive cases, the response is immediate, hfi recovery is very rapid after the ice is
removed. The esptession, ^prolonged pain," signifies slow recovery and lingering pain. The
imtW re^onse to the ice may be fapid or slow. TMs test ^qvIA always be csetrled out by
comparing adjacent and corresponding teeth. Only because of the relative difference in reaction,
is this useful. Failure of one tooth to respond to ice should suggest a nonvital pulp. It has been
frequently observed that patients attempt to cover teeth with the tips of their tongues in the
case of prolonged pain from ice. (Ice or ethylchloride on cotton may be used.)
17. Extreme sensitiveness to appUcation of heat would indicate pulpal degeneration.
18. The final clinical test is the removal of suspected restorations and curettement of
carious lesions if present, with particular attention to exposed pulp horns. Exposures do not
always show an infection, but use of a sharp explorer, with some pressure, will usually (Isckise
the concealed exposure area. Staining the lesion with an aqueous iodine solution or ^tttian
violet win often marte the exposed sffea.
19. Repeated decompression tests win confirm a doubtful diagnosis.
Dif^ostic Procedures for Medical-Dental Problems
Maxillary aerosinuatis is the most common medical-dental problem causing refewed pain to
the teetil and necesdtalwtg a differential diagnosis. Chronic aerotitis media may cause orofacial
pain relating to the temporomandibular joint and posterior border of the mandibular ramus on
the iivolved side.
Aerosinusitis. Referred dental pain from aerosinusitis usually involves those teeth whose
root structures are closely involved with the maxillary sinus on the involved side, i.e., the
posterior maxillary quadrant, bicuspids, and molars.. The pain usuaHy occurs during descent and
may continue after completion of the flight. There is usuaUy a history of nasal congestion,
12-7
U.S. Naval Flight Surgeon % Manual
nasopharyngitis, or sinusitis, but patients often do not relate these to the dental symptoms.
Complaints vary from burning and tingling sensations in the mucobuccal fold to headaches
above and behind the eyes, numbness or pain in the maxilla on the involved side with
%p^iieda or paregthesia of the ihfi-aorbital'iirea, and cfental-related pain, usually to percussion,
involving one or more teeth in the associated quadrant.
Diagnostically, there is usually dull pain or discomfort to percussion of all teeth in the
involved quadrant. There is pain to moderately firm palpation intraorally over the lateral
maxillary sinus wall high in the mucobuccal fold superior to the bicuspids and molars.
E3dT4ora%, Acre may be simflw psm to percussion infraorbitally and over the malar eminence
ofthezy^ma.
Radiographs and transillumination ar^ usually of little help. Dental radiographs will aid in
affirming or ruling out dental-related pathology if symptoms are strong in that direction.
WatfflS' and Caldwdl views of' facial structures will reveal thickened sinus mucosa in chronic
cases. M views and transtUuminafion will ik&w elose association betwe^ flie roots of flie teeth
and the ]!na3:ilkry sinus floor, which is considered 'normid no matter jfiow protubetatit they
appear.
Aerotitis Media. Aerotitis media, discussed much more completely in the chapter on
otorhinolaryngology, is usually caused by blockage of the pharyngeal end of the eustachian tube
filing descent of an aircraft. The patieiit, because of swelling or edema of tlie eustackm tube
or surrounding adenoidal tissue, is unable to "clear" the tulbe by 4e normal
procedures - yawning, swallowing, or Valsalva maneuver. If the blockage remains for several
days, the patient may develop symptoms which could include vague temporomandibular joint
pain and pain along the posterior border of the mandibular ramus and the anterosuperior border
of tl^ sternocleidomastoid muscle.
Dental Records and Terminology
The Flight Surgeon should possess a working knowledge of the human dentition,
terminology, ^d records, as a means of faoiiliyii^lus interaction Wiii Dental Officers. Such
interaction oceuis most frequency in disorders requiring differential diagnosis and iii accideiit
investigations involving the identification of deceased persons through human dentition.
Chapter IV, Articles 107-121 of the Manual of the Medical Department describes the
terminology and recording techniques utilized in dental records.
12-8
Dentistry
The Dental Record
The Dental Record, DD Form 722-1, contains several items of information, the most
pertinent being Standard Form 603 (Figure 12-1). SF-603 haa two major sfedtioiis on the front
side:
1. Item 4 of Section 1 reveab missing teetii and existing restorations with amplifying
remarks.
2. Item 5 of Section 1 reveals diseases, abnormdities, and X-rays as noted at the time of
examination.
The reverse side is a chronological record of treatment accompliBhed and diseases and
abnormalities that become apparent during subsequent examinations.
Current radiographs, either bite-wing X-rays of the posterior coronal dentition or Panorex
X-ray of lower and mid-face struetures, will be inchided as well as less pertinent stfflidard forms.
Dental records are c^lor-coded on the outer leading edge for quick appraisal of five classes
of possible dental problems.
Class I (white) - no treatment necessary
Class II (green) — minor treatment required, not immediate
Class in (yellow) ~ a^aificant treatment required, may be problematic, treatment
as soon as possible
Class IV (dark blue) - treatment requiring prosthetic replacement, not immediate
Class V (red) - dentd emergency, top priority, immediate treatment required,
may be a serious health problem.
Tooth and Tooth Surface Designations
The normal adult dentition consists of 32 teeth. These are numerically designated by their
position in the dental arches. The maxillary arch contains teeth 1-16 beginning cireumferentiaUy
with the ri^t third molar (1) and continues tb 4e left ted molar (16); tiien, the numbering
continues in the mandible from left to ri^t be^nning with the left third molar (17) and ending
with the right third molar (32) (Figure 12-1).
The surface of a specific tooth is defined as one of five possible aspects; occlusal (incisal for
anterior teeth), facial, mesial, lingual, and distal. Figure 12-2 depicts these aspects for anterior
129
U.S. Naval Fli^t Surgeon's Manual
12-10
Dentistry
and posterior teeth. These aspects are used individually or in combination to identify the
position of caries, defects, or restorations. Abbreviations for tooth surface terms are as foUows:
Surface
Facial (labial and buccal) ,
lingual
Occlusal
Mesial
Distal
Incisal
Designation
F
L
0
M
D
I
Examples of how these terms would be used in combinations are: 22-DF, the facial and
distal aspects of the left manidublar cuspid; 30-MODF, the mesial, occlusal, distal, and facial
aspects of a right mandibular first molar.
MEDIAN
LINE
INCISAL
EDGE
OCCLUSAL
SURFACE
MESIAU SURFACE
DISTAL SURFACE
Figure 12-2. Surface designations of anterior and posterior teeth
(from U.S. Naval Fl^t Surgeon's Manud, 1968).
Definitions
The median line is an imaginary perpendicular line that passes between the central incisors
in each arch corresponding with the mid-palatal suture in the hard palate.
1. Facial — the surface facing the hps or the cheete
2. Lingual — the surface facing the tongue or hard palate
3. Occlusal — the grinding surface of a posterior tooth
12-11
U.S. Naval FU^t Surgeon's Manual
4. Incisal — the cutting edge or surface of an anterior tooth
5. Mesial — the surface facing the median line
6. Distal — the surface facing away from the median line.
Restcffofioiu and Regtorative Materials
Dental restorations are made front several types of materials. Eaeh type is brte£ly described
induding the technique for record identification as pertaining to the type of restorative material
used:
Silver Amalgam — This alloy restoration presents a silver or black iqipearance on oral
examination. The dental record indicates these restorations by a solid black mark of the same
size, shape, and location as the restoration.
Nonmetallic — NomnetaQic restorative materials most frequently used are topth-cdiored
silicates, porcelains, or plastics. Recording of these restorations is accomplished by outlining
size, shape, md location of the restoration on the dental chart.
Gold — The dental record indicates gold restorations by horizontal, parallel lines within the
outline of the restoration.
Missing and Replaced Teeth
Missing teeth are indicated on the dental record by placing a large X on the root or roots of
each txtoQi that is not nsiMe. Common replacements for missing teeth are complete dentures,
removable partial d^tures, or fixed partial dentures. The recording techniques used to indicate
replaced teetii are
Removable Prostheses — A line is placed over the nimibers of the tee& replaced and ibe
prosthesis is described briefly in the Remarks section.
Fixed Pmiial Dentures — Each aspect of a fixed partial draiture is outlined, showing size,
location, fhape, and teeth involved. The ^mbols for materials a^ 0m $ame as for restorations,
^cept that gold is shown by diagonal rather than horizontal lines.
Crowns — Crowns are used totestore lost tooth structure. The material for crowns is usually
gold or poreelain, or a combmation of the two. Hie method for recoirdittg crowns (not involved
with fbced prostheses) is to outline the size, shape, and location on the affected tooth.
1212
Djentistry
Abbreviations
Authorized abbreviations used in dental records are presented below.
Operation, Condition, or Treatment
Abscesa
All Caries Not Removed .....
M Caries Removed ......
Ahreolectomjr .........
Amdeam
Aneauietiic(theaia)
Apicoectomy
Base
Camphorated Paramonochlorophenol
Cement
Cojp^|l?<ie Denture .......
Growii ...........
Curettage
Drain . . .
Dressing
Equilibrate(ation) ....
Eugenol . . •
Examination
Extraction(ed)
. li^edJfertiel Dentiwe (Bridge)
ire
Abbreviation
Abfi.
ACNR
ACR
Gingivitis
Guttapercha , . ; .
Mandibular . . i
Maxillary
Navy Periodontal Disease Index
Navy Plaijue Index
Necrotizing Ulcerative Gingivitis
Pericoronitis '
Periodonitis •
Plaque Control Instructions .............
Point(s)
Porcelain
Postoperative Treatment .
Prophylaxis ^ •
Reline
Removal Partial Denture
SSSlHIlilig' R(*
Root Canal Therapy ................ RCT
Scaled(ing) Sd,
Am.
Anes.
Apcy.
B.
CMCP
Cem.
CD
&.
Gitt.
Ihm.
Drs.
Equil.
Eug.
Exam.
Ext.
FPD
Gvtis.
G.P.
Man.
Max.
NPDI
NPI
NUG
Pecor.
Pdtis.
PCI
Pt(s).
Pore.
P.O.T.
Pro.
Ret.
RPD
Rep.
Self-Preparation
SiUcate . . .
Surgical . .
Sutuie(sXd)
Temporary .
'h;eatment(ed)
Vamidi . .
SP
sa.
Surg.
Su.
Temp.
Tr.
Vam.
12-13
U.S. Naval Fli^t Surgeon's Manual
References
Burket, L.W. Oral medicine. Philadelphia: J.B. Lippincott Co., 1946.
Department of the Navy, Bureau of Medicine and Surgery. Manual of the medical department.
Department of the Navy, Bureau of Medicine and Surgery. Preventive Dentistry Manual (NAVMED 5087).
Department 0£ the Navy, Buie«a of Medidae and Suiwery. Preventive dentistry programs
(SICNAVINST 6^,1B). 197T.
Orban, BJ., & Ritchey, B,T. Toothache under condition simulating high altitude fS^Ljourtud of the Amaican
Dental Association, 1945, 31, 145-180.
Sognnaes, R~F. FurAet studies aviation dentistry: Umui symptoms reported by filter pilots exposed to
prolonged, hi^ altitiule operations. Acta. Odont, Seandinmia, 1947, 7, 165-173.
U.S. Naval Flight Surgeon's Manual. Prepared by BioTechnology, Inc., under Contract Nonr-4613(00). Chief of
Naval Operations and Bureau of Medicine and Surgery. Washington, D.G., 1968.
Bibliography
Department of the Navy, Bureau of Medicine and Surgery. Aviation medidne prajCtice (NATI^II^ 10839A).
DeWeese, DJ)., & Saundas, W.H. Teictbook of otolaryngology. St. Louis: TheC.V. Mosby Comp^py, 1973.
Shafer, W.G., Hine, M.K., & Levy, B.M. A texthook of oral pathology. Philadelphia & London: W.B. Saunders,
Co., 1958.
12-14
n
c
c
CHAPTER 13
MEDICAL DEPARTMENT PERSONNEL
Introduction
The Hospital Corpsman
The Medical Service Corps
Conclusion
Introduction
The medical department is charged with the responsihility for all factors affecting the
health and well-being of Navy personnel. The mission of the medical department can be
broaifly defined as "the maintenance of the health of the Navy and Marine Corps and the
care of the sick and. injured in peace mA war." The functional integration necessary to
accomplish this mission is achieved through the efforts of all members of the medical
department. Medical department personnel consist of the Medical Corps (physicians),
Dental Corps (dentists). Nurse Corps (nurses). Medical Service Corps (MSC's), the Hospital
Corps, and Dental Technicians (eidisted personnel). Contact with Nnm Craps officers may
be minimal. Dental Corps officers and dental techincians id»3ard cmiers augment halUe
dresang stations during general quarters, assist in triage during mass casualties aboard ship,
and the oral surgeon also often acts m, the anestfietist in the operating room. Their
contribution to the medical department mission is recognized and vital. Further informa-
tion regarding these two officer staff corps may be found in chapters 6 and 8 of the
Manual of the Medical Department.
The Flight Surgeon is an important member of the Navy Medical Coips; however, to
accomplish his task successfully, he is dependent on support from his colleagues on the
Medical Corps team. He requires professional paramedical, administrative, and logistic
assistance to enable him to practice aviation medicine most effectively. By the very nature
of the Flight Surgeon's operational mission, he is often remote from the usual professional
support available to the medical officer at a branch dinie,' a naval hospital, or a naval
regional medical center. It is imperativie that the Fli^t Sui^oa he familiar with #e
qualifications, training, and capabilities of the other medical department personnel to
enable him to fulfill his obUgations as a Navy medical officer.
13-1
U.S. Naval Fli^t Surgeon's Manusd
The Hospital Coqpsman
The Navy hospital corpsman is a member of the Navy medicd d^ptmejit who shares in,
and is indispensable to, direct patient care. Although hospital corpsmen may possess different
levels of training and expertise, all of them exhibit professionalism, pride, and dedication to the
Navy and the mission of the medical department. They have gained respect by their enthusiasm,
intelligence, support, professionalisni, atnd versatility. Frequeantly, they are called upon to
perform ti^ks other than the traditional corpsman, patient-oriented duties. Hospital corpsmen
pride themselves in tfie saying that "a corpsman can do anything" and have proven it in many
ways. Hospital corpsmen have distinguished themselves both in time of peace and war, and
official recognition of their exceptional heroism, devotion to duty, and humanitarian service to
mankind has resulted in iheir becoming one of the most highly decorated military groups.
As versatile as ^ey are, corpsmen need continued training to be of maximum benefit to the
medical department. Training allows corpsmen to compete favorably for advancement in rate,
to achieve new and better skills, and to broaden their perspectives and horizons. Additionally,
such training provides a medical department with an indepth reserve of competence which
enables it to react effectively to any emergency situation.
Hbspil^ cdirpstiieh lecdfre their hiade medical indoetrihattton at Hospital €,6tp6 School. The
length of the course has varied through the years. Currently, the curriculum includes the
following core courses: Anatomy and Physiology, Environmental Health, Drug Therapy,
Emergency Care, Patient Care, Medical Mathematics, and Administrative/ Military Training.
After Hospital Corps School, many corpsmen proceed to their first duty station to acquire
oii-^flie-job training and to put liieir newly learned theoretical knowledge to practical use. The
initial duties vary, but most are ass^ed to a health care activity in a direct patient care
environment. After his initial duty, the corpsman may apply for advanced courses of formal
instruction to achieve designation as a technician in his areas of interest. Courses that the
hospital corpsman may apply for are listed in the Medical Department Formal Schools Catalog.
A listing of the current specialties and their Navy Enlisted Classifications (NEC's) follows:
-3391 Nuclear Power Plant Operator - CE, EO, CM, SW, UT, HM
-3398 Nuclear Power Plant Operator - Special Category, CE, EO, CM, SW, UT, HM
HM-8294 In-Plight, Medical SpeciaHsl
HM-8402 Nuclear Submarine Medicine Technician
. HM-8404 Medical Field Service Technician
-1 HM-8406 Aerospace Medicirie Technician
. . RM-8407 Nuclear Medicine fechraelan
IIIi$>8^ Cy^t^pfuMonary T^y^^ ^
HM-8409 Aerospace Physiology Technician
Medical Department Personnel
HM-8416 Clinical Nuclear Medicine Technician
HM-8422 Physician's Assistant Trainee
HM-842S Advanced Ho^ital Corpsman
HM-8432 Preventive Medicine Technician
HM-8433 Transplantation Technician
HM-8444 Ocular Technician
HM-8445 Advanced Ocular Technician
HM-8446 Otolaryngology Technician
HM-8452 X-Ray Technician
HM-8454 Electroencephalography Technician
HM-8463 Optician Technician
HM-8466 Physied and Occupational Therapy Technician
HM-8472 Photography Technician
HM-8477 Biomedical Equipment Technician, Basic
HM-8478 Biomedical Equipment Technician, X-Ray
HM-8479 Biomedical Equipment Technician, Electronic
HM-8482 Pharmacy Teehnieian
HM-84B3 Operating Technician
HM-8485 Neuropsychiatry Technician
HM-8486 Urological Technician
HM-B489 Orthopedic Cast Room Technician
HM-8492 Special Operations Technician
HM-8493 Medical Deep Sea Diving Technician
HM-8495 Dermatology Technician
HM-8496 Embalming Technician
HM-8501 Laboratory Technician, Basic
HM-85D2 Histology Technician, Basic
HM-8503 Histology Technician, Advanced
HM-8504 Cytology Technician, Basic
HM-8505 Cytotechnologist TeGhnician
HM-8506 Medical Laboratory Technician, Advanced
HM-8507 Medical Technologist
HM-8531 Intensive and/or Coronary Care Technician
llM-8541 Respiratory Care Technician
HM-8591 Audiometric Technician
Corpsmen may apply for correspondence courses in medical as well as other adminis-
trative and military subjects at any time. Further opportunity for degree candidacy in
part-time outservice training is available in a variety of academic institutions both ashore
■and at sea.
13-3
U.S. Naval Flight Surgeon's Manual
Hospital corpsmen who have achieved the rating of Chief Petty Officer deserve special
mention and recognition. It has been acknowledged throughout the history of the Navy that the
Navy Chief Petty Officer is the backbone of the Navy. This is especially true aboard ship where
Chiefs are in close daily contact with each otiiec. MostHavtd officers can recall difficult
situations which appeared to defy satisfactory solution, only to have the problem resolved
without fanfare when tackled by "the Chief." A great many things "happen" without official
request or notice which are indispensable to the smooth functioning of any Navy unit. In his
o^ial capacity and specialty, a Chief Petty Officer is a competent Navy professional. One does
not advance to ijie rating without the proper credentials. The skills and savvy of a Chief Petty
Officer are acquired only by hard work and perseverance.
In my group of corpsmen, one or two will stand out as being superior to tiie others. They
will possess a "certain something" that sets them apart from their pee*s/ It becomes incumbent
upon each medical department officer to cultivate, encourage, and direct these outstanding
corpsmen to aspire to become MSG officers. There is a sound philosophy that the corpsman
who exerts that extra effort to improve himself academically, as well as professionally, deserves
recognition and the opportunity to compete for a commission. Proven academic performance at
the college level is interpreted as an indication that the candidate possesses motivatibn to
continue college level studies. An enlated person, once commissioned, is expected to attfun a
baccalaureate degree. If the candidate is successful in obtaining a commission, he should be
advised to apply for admission to the Naval School of Health Sciences (NSHS), where he will
receive specialized training in all aspects of health care administration. The Naval School of
Health Sciences is affiliated with George Washington University, and college credits may be
granted for successful completion of various courses. Thus, some officers witii previously earned
college credits may simultaneously receive their baccalaureate degree from George Washington
University at the time of their graduation from NSHS. Others complete any remaining
requirements shortiy thereafter, and then receive their baccalaureate degrees.
The Medical Service Corps
A Medical Service Corps officer works closely with all members of the Navy medical
department, and he may be involved in direct patient eare, health care administration^ medical
reseuch, training, or the practice of a wide variety of modem medical scientific ^ecialties.
The Medical Service Corps is composed of six sections with a further categorization by
specialty within each section:
Health Care Aibfdnistration Secticra
Administrative Officer, Medical Service
V. Administrative Officer, Dental Service
134
Medical Department Personnel
Patient Affairs Officer
Food Service Officer, Medical Facility ■
Opnerations Mani^enii^t Officer, Medical Facility
Medical Facilities Liaison Officer
Staff Medical Service Corps Officer
Staff Medical Service Corps Officer (With Marine Corps)
Medical Allied Science* Section
Biochemist
Microbiologist
Pharmacologist
Radiation Health Officer
Radiation Specialist .1.
Physiologiat
Aerospace Physiologist
Clinical Psychologist
Aero^ace Expe^mented Psy^otoi^t
Research Psychologist
Entomologist
Environmental Health Officer
Industrial Hygiene Officer
Medical Technologist
Medical Specialists Section '
Physical Therapist
Occupational Therapist
Dietitian, TTierapeutic
Optometry Section
Optometrist
Pharmacy Section
Pharmacist
Podiatry Section
Podiatrist
MSG Healtii Care Ado^nistralor <
Currentiy, only an MSC Health Care Administrator (HCA) serves aboard ship with the Flight
Surgeon. This section will amplify on tiie relationship of the Flight Surgeon to the MSC Health
13-5
U.S. Naval Flight Suigeori's Manual
Care Administrator. Further information regarding duties of the Medical Service Corps may be
obtained from Chapter 7 of the Manual of the Medical Department.
The Flight Surgeon should consider the MSG Health Care Adttimistrator as a priiuary source
of support and assistance. As a sp^ialist in the administration and mms^taeAmt pecttliarities of
the Navy system, his expertise is an essential ingredient for the successAil operation of an afloat
medical department.
The Health Care Administrator is obtained from two sources: (1) in-service procurement,
whereby qualified Navy enlisted hospital and dental corpspefsons are afforded the opportunity
to obtain a commission, and (2) direct procurement, whereby college grjMhl«te8 with special
academic qualifications are offered a direct commission from civilian life. The resultant
admixture of officers with advanced formal education and officers with a basic formal
education fortified with prior medical department experience is considered to be advantageous.
As described previously, Medical Service Corps officers from both sources are provided
additional appropriate training in health care administration.
Hie MSG Aboard Ship
Aboard ship, the MSG officer spends a major portion of his time in sickbay where he is a
ready point of contact at all times. In addition to being the medical administrative officer, he is
usualy the division officer as well. The enlisted staff readily identifies with the MSG officer
since in the vast majority of cases he has progressed through the hospital corps ratings and can
he quite responsive to their particular needs.
The MSG officer aboard ship, as well as ashore, should be the Flight Surgeon's pimaiy
contact for the solution of medical administrative problems. Except in purely medical treatment
matters, the MSG officer should be able to reheve the SMO (Senior Medical Officer) Flight
Surgeon of many of the routine administrative, personnel, and supply functions which are
required of a shipboard medical department. Nevertheless, it is important for any physician to
know medical administration in order to develop tiie insight necessary to successfully interact
with line officers.
There are administrative and management decisions every Flight Surgeon must make. They
are easier to make when all the facts are at hand, and all the alternatives can be considered. The
medical administrative officer is conversant with all types of administrative matters. He is
invaluable to the Fli^t Surgeon in his aiea of expertise and should be tasked and utilized to
maximum advantage, permitting the Flight Surgeon to make decisions relative to the duties of
medical department personnel When an administrative decision is required by the Flight
13-6
Medical Department Pereonnel
Surgeon, he will have the necessary information at hand on which to make a sound and logictd
judgement. The Flight Surgeon's direct patient care duties are quite clear, hut many other tasks,
questions, and problems outside the sphere of direct patient care arise. These questions and
problems should, whenever possible, be referred to &e MSG officer for resolution, input,
research, or further discussion. Day-to-day msmagement of a sh^board medical department
necessitates familiarity and involvement with personnel, supplies, battl-; dressing stations, drills,
emergencies, patient evacuation, sanitation, reports, immunization, inspections, correspondence,
watches, duties, liberty, haison, discipline, inventories, narcotics and dangerous drugs,
department relationships, sickcall, decedent affairs, collateral duties, directives, in-service as well
as ship-board training, NBC matters, mass casualty preparedness, etc. These and other related
responsibilities may be properly ddegated to the MSG officer with confidence. He may not have
enough time to perform all tiiese assignments himself, but he wiU assure that they are
accomplished in an efficient and timely manner. In this functional role, the MSG officer
provides invaluable service to the whole medical department, and to the Flight Surgeons in
particular, by assuming responsibility for the myriad of administrative duties and thereby
affording the Flight Surgeon increased time for patient care and atteiitioK to ihe safety and
weU-bdng of ship's company and the embarked air wing.
Conclusion
The effectiveness of an afloat medical department is not measured solely by the patient
statistics contained in its monthly morbidity report. A more realistic appraisd would include
the department's non-reportable efforts directed towai-ds preventive medicine, aviation an4
industrial safety, and the maintenance of a posture of medical readiness to react to any
emergency situation. These goals can only be attained by implementation of the concept of
mission achievement as a result of coordinated team effort. Each medical department officer
and man is a valuable asset and, as a member of the team, must contribute his best effort,
toward the accomphshment of the overall mission.
13-7
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CHAPTER 14
AVIATION MEDICINE WITH FLEET MARINE FORCES
Introduction
Personnel and Training
Organization
Medical Duties
Cautions
Conclufiioti
bitroduction
The outward appearance of sameness that exists at a technical level in the Marine and Navy
components of naval aviation overUes differences that often are significant. The Marine aviator
serving with a Fleet Marine Force works in an organizational structure which is similar to, but
not identical with, that of his Navy counterpart. His basic attitudes and assumptions may differ
to some extent from those of his Navy peer. Whik a complete description of these differences
and their subtle eoiis^gnees is beyond tfie scope of ihis taamd. It is important for any Navy
Pii^ Surgeon ordered to duty with the Fleet Marine Force to understand that the differences
do exist. They may appear in unexpected ways; they may be subtle, and they can be ignored
only at the risk of significantly reducing one's effectiveness with a Marine unit.
This chapter presents background information helpful in understanding Mmnes and their
organization. No atteinpt is made to discuss dispositions of specific aeromedical problems, ^
they rarely differ significantly from those encountered in Navy organizations.
Personnel and Training
Procurement
The Marine Corps obtains iU prospective officers from a population as geographically and
cuituraUy diverse as any other service. A percentage of Naval Academy graduates, as weU as
graduates from Naval Reserve Officer Training Corps (ROTO) programs, are commissioned in
the Marine Corps. A large percentage of Marine officers enter by way of the Hatoon Lea^rs
Class (PLC), a variation of ROTC in which college students undergo two, six-week summer
training sessions at the Marine Corps Development and Education Command (MEDEC),
Quantico, Virginia, prior to commissioning upon graduation from coUege. A smaU, but
14-1
U.S. Naval Flight Surgeon's Manual
significant percentage of Marine Corps officers are obtained from the highly competitive
Enlisted Comtmssjoning Program. These "Mustang" officers hiiaag to the Corps a depth of
understanding of the enlisted communis that pcob^ly Caniiot be obtained in any other way.
Their competitiveness for advancement is limited only by their ability; in 1976, the Marine
Corps promoted to Brigadier General a man whose first eight years of service were as an enlisted
rifleman.
Basie Training
A distinguishing feature of ihe Marine aviator is that his first six months of commissioned
service are spent, almost without exception, as a student at the Basic School (TBS), %an^cQ,
Virginia. TBS provides just what the name implies — a basic core of knowledge and experience,
heavily oriented toward the basic infantry mission of the Marine Corps. TBS is probably more
responsible than any other factor for insuring that the proper "state of mind" will exist in all
Marine officers, and that this state of mind will persist despite later training as an aviation or
infantry officer. In addition, this introduction to the basics of ground warfare provides the
^ttil^ aviation officer with an understanding of the infantry forces he will someday support.
Basic Aviation Traiiiing
Basic aviation training for Marine pilots Mid flight officers is completely integrated with that
of their Navy peers. Squadrons in the training command can, at any given time, be commanded
by a Navy or a Marine officer. Most squadrons have both Navy and Marine instructors, each of
whom has assigned to him both Navy and Marine students. The importance of this goes far
beyond any cost savings that are made through increased efficiency. Rather, it is basic to the
fact that aU Marine pilots are indeed "naval aviators."
Advanced Aviation Training
Following basic training, a young Marine naval aviator or naval flight officer (NFO) is
assigned to a Marine Aircraft Wing (MAW) for training in a specific Fleet aircraft. Although he is
trained solely by Marines in a Marine organization, NATOPS and Navy/Marine training
conferences insure that his training is techmeally the same as that received in the same model
tdrcraft in the Navy. Following the attainment of basic qualifications in a Fleet aircraft, most
aviators and NFO's are ordered to one of the three Marine Aircraft Wings. If sent initially to the
Second or Third MAW, located on the East Coast and West Coast respectively, he is normally
transferred again to the First MAW in the western Pacific during his first four years following
designation as an aviator or NFO.
14-2
Aviation Medicine With Fleet Marine Forces
Further Aviation Training
Two types of later training distinguish the Marine pilot from his Navy counterpart.
Assignment To Differenf Aitcmft. The majoRty of Navy pilots can anticipate a full cai%
flying in one of the three basic communities - tactical jet, rotary wing, or patrol/transport. Not
infrequently, all of a Navy pilot's flight time foUowing basic training is logged in the same type
of aircraft. A Marine pilot, however, at the Lieutenant Colonel or Colonel level, will frequently
have served full tours in two or three of the basic communities, and he may have significant
time in several different aircraft v^thin a community.
Liaison Tours With a Marine IMvMm. Each rifle battalion and rifle regiment of a Marine
Division rates several fully -trained naval aviators to serve as Forward Air Controllers (FAC) or
Air Liaison Officers (ALO). Aviators to fill these billets are normally provided by the nearest
Marine Aircraft Wing for tours of four to six months each. After spending a considerable
amount of time in the field at a rifle company level, these aviators bring to the infantry unite
the expertise to define the capabilities and limitations of the aircraft wWdi ^ infamtif
commander might have supporting him. Of no small importance is the understanding the
individual aviator gains of the problems faced by infantry units which might someday call on
him for support in an actual combat situation.
Organraation
Fleet Marine Forces
The operating forces of the Marine Corps are currently organized into two Fleet Marine
Forces (FMF), Fleet Marine Force Atlantic (FMFLant) with headquarters in Norfolk, Virginia
and Fleet Marine Force Pacific (FMFPac) with headquarters in Honolulu, Hawaii. Each FMF
reports to the Commander-in-Chief, Atlantic or Pacific Fleet (as appropriate), is equivalent W a
Navy-type command, and is commanded by a Lieutenant General (Navy equivalent - Vice
Admiral). The Commanding General may be either an aviator or a ground officer. Whatever his
background, it is normally complemented by having a Deputy Commanding General from the
other community.
Each FMF consists of at least one Marine Aircraft Wing (MAW), one Marine Division
(MARDIV), and one Force Service Support Group (FSSG). Other miscellaneous supporting
units may be attached.
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U.S. Naval Fli^t Sui^nV Manual
FMFLant
The aviation arm of FMFLant is the Second Marine Aircraft Wing, headquartered at Cherry
Point, North CaroHna. Second MAW's tactical jets are located at Cherry Point, North Carolina
fiitttf at Beaufort, South Carolina. Helicopters are located at New River, North Carohna.
FMFPac
FBIFPae spam entire Va&Sc area, fr^in Amotta to J*^. In the western Pacific is tiie
First Marine Aircraft ¥ing, with headquarters and helicopters on Okinawa and tactical jets at
Iwakuni, Japan. The First Marine Brigade is located in the raid-Pacific near Honolulu, Hawaii.
The brigade has assigned smaller numbers of tactical jets and heHcopters, as well as an infantry
element, and is in effect a smaller version of the normal wing/division air-ground team. The
TMrd Mwnm Airerirft.]5{ing is located in the eastern Pacific, with headquarters and some tactical
jete at ElToro, CaHfomia, other tactical jets at Yuma, Arizona, and helicopters at Santa Ana
and Camp Pendleton, California.
Marine Aircraft Wing
A Marine Aircraft Wing is commanded by a Major General (Navy equivalent - Rear Admiral
[Upper Half]). It is important to remember that a Marine Aircraft Wing is much larger than a
Navy Carrier Air Wing. Assigned to each wing is a majority of the types of aircraft in the Navy
inventory, (First MAW currently has asa^ned F-4, A-4, AV-8, TA-4, A-6, KC-130, OV-10,
CH-53, CH-46, UH-1, AH-1, G-117, RF-4, and EA e aircraft.)
Unlike the Marine Divisions, which are oi^anized along fairly standard lines, each MAW is
task-organized, i.e., has different component units, depending upon the mission assigned.
Typically, a wing consists of a Marine Wing Headquarters Squadron, a Marine Air Control
Group, a Marine Wing Support Group, and several Marine Aircraft Groups.
Wmi^ti Aircraft Group
Normally, a Marine Aircraft Group (MAG) consists of a Headquarters and Maintenance
Squadron, a Marine Air Base Squadron, and several (nominally three to six) aircraft s(]piadrons.
Different types of aircraft usually are grouped by basic mission, e.g., tactical jet fighter, tactical
jet attack, helicopter, and transport. However, variations do occur, usually because of
availabOi^ of base facilities and particular training areas.
Medical Organization
Each wing has assigned to it a senior Flight Sui^eon (normally a Captain) as the Wing
Medical Officer. He is assisted by a Medical Service Corps officer, a Master Chief Hospital
144
Aviation Medicine With Fleet Marine Forces
Corpsman, and a small office staff. The Wing Medical Officer functions on the Wing Special
Staff, coordinating Medical Department personnel assignments, supervising the activities of
assigned junior Flight Surgeons, assisting in the overall awatiOH safety program, and providing
appropriate general medical, aeromedical, and Navy personnel advice to the Commanding
General and General's Staff.
Junior Flight Surgeons are nominated by BUMED detailers and assigned by the Bureau of
Naval Personnel to the largest organizational unit consistent with geographic limitatioil^
imposed by Navy assignment policies. Further assignments to individual squadrons are iiM
made by the Wing Commander, on the advice of the Wing Medical Officer. The ideal case ia
represented by First MAW in which all Navy personnel are assigned to the Commanding General
for duty. This aflows for sub- assignment within the Wing to meet the changing need^ of the
command and, where possible, the desires of the individual Flight Surge($ii.
Medical Duties
The general duties of a junior Fhght Surgeon attached to a Fleet Marine Foree can he
grouped into five broad categories.
Outpatient Clinical Medicine
Depending upon the unit to which attached and the arrangements made by the local
commmid, some percentage of tiie FH^t Surgeon's time normdly Tvill be qpent in an outpatient'
medical facility, erthet at an out-lying clinic or in the outpatient departraeat of a naval hospital.
The patient mix - active duty aircrew, active duty non-aircrew, dependent, and retired - will
depend on the locality. Under such circumstances, the Fhght Surgeon works under the
professional direction of the clinic senior medical officer or the chief of the department.
Aviation Medicine Department
Depending upon local arrangements, the Aviation Medicine Department or tiie Avijatiidtt
Examination Room might be involved in drcrew physical examinations, aircrew sick call, or
both. '
Squa^onTune
Normally, one will be assigned to one or more squadrons, and possibly to the group as weU.
This presents a challenge in the management of time. It will be necessary to cover many areas of
responsibility without spending too much time in any one place. There will be presentattoBfi at
all officer meetings (AOM's). At a squadron level, it is not enough to know all of the pilots
personally. One should also have an understanding of the unit safety program and of programs
14-5
U.S. Naval Hi^t Surgeon's Manual
that are currently being emphasized by the command - programs that may have little to do
directly with safety, but which may influence safe flight operations by their effect on the state
aft rest and morale ^ airerew personnd. In addition, a Flight Surgeon should log some amount
of time flying with the squadron.
Attention should be paid to the enlisted work spaces, particularly the maintenance shops.
Not only do these maintenance areas contain significant industrial hazards, but the maintenance
effoi* is also not hkely to be better than the men doing the job.
Shipboard Dcployitients
MAW's provide composite helicopter squadrons to deployed LPH^ (Landing Platform
Helicopter - essentially hehcopter aircraft carriers); they also provide the Flight Surgeon. In
addition, Marine tactical jet squadrons occasionally deploy onboard aircraft carriers. Althou^
the Flight Surgeon works as an integral part of the shipboard medical department, and every
reasonable effort should be made to make that working relationship as smooth as possible, one
^ould not lose sight of the fact that one's primary responsibility is to the Marine squadron to
which attached.
Field Training Exercises
Marine squadrons, usually hehcopter but occasionally tactieal jet, participate in field
exercises supporting various units from the Marine division. Under such circumstances, the
Flight Surgeon frequently has overall medical responsibility for the health and sanitation of all
personixd living in a camp, as well as his normal aeromedical concerns. Although preventive
medicine technicians attached to the Wing Medical Officer's office can provide invaluahle
assigtance snd technical guidance later, there is no substitute for becoming involved at an early
stage in the planning of the exercise. The Flight Surgeon should understand clearly what the
camp commander expects, and the commander, in turn, should understand clearly what can and
cannot be provided. Availability of back-up medical services, availability of patient trans-
portation, definition of patient categories leading to evacuation, chain of command for
approving medical evacuation, anticipation of peculiar medical problems, and medical supply
and re-supply should all be conddered and planned for in advance. If possible, there should be a
discussion with the medical officer who went on the last exercise. If this is not possible, the
"Lessons Learned" report which he submitted should be closely examined. Each Flight Surgeon
should document his own experiences and insure that they are included in the command's
sAer^action report.
14-6
Aviation Medicine Wilh^FteetMaipine Forces
€mla.om
Conduct
Marines are tremendously proud of their heritage. As such, they normally respond very
favorably to a medical officer who wears hfe unifofifl with pride, conforms to grooming
stoidafds, mMntains their pace in physical conditioning, and genefiDy conducts himself in the
manner expected of a young Marine officer. Because tli«y respect their profession, they
naturally will respect the Flight Surgeon's, provided he remembers what it is. His job is to give
Marines professional medical advice, tailored to the unique requirements of their society and
their mission. His job is not to be a pilot or flight officer, a squadron commander, or a tactical
expert.
Rank and Forms of Address ^
Just as in a hospital, forms of address for different personnel have evolved in the Marine
Corps. The Flight Sui^eon diould learn them and become comfortable using them. Although
some of the conventions may seem somewhat stiff, they nevertheless serve a subtle but
important purpose. They tend to remind one that in a structured system, one's relation to
another is largely defined by the mission and the requirements of the job, not by one's personal
friendships. This does not mean that a more informal approach cannot be used when called for
by one's role as a physician. Rather, it su^ests that this should be the justification in spectfifc
cases, rather than a blanket excuse to ignore one's position as a naval officer.
Enlisted. All enlisted personnel can be properly addressed by rank, with or without last
name attached. Gunnery Sergeants (pay grade E-7, equivalent to a Chief Petty Officer) are
almost universally addressed as "gunny." First Sei^ants and Master Sergeants (both pay gEJSfe
E-8) are usually referred to as "top." Master Gunnery Sergeants (E-9) are also often referred-^
as "top." Most important, a Sergeant Major (E-9) is referred to in only one way - "Sergeant
Major." The term "sarge" is occasionally used, but is improper and should be avoided. The term
"sir" is never used in talking to enlisted personnel; it will frequently be interpreted as, a
put-down and will have an effect opposite to that intended. »'>
Wamint Officers. Marine Warrant Officers are referred to as "gunner. "
Commissioned Officers. Officers junior to the speaker are referred to by their rank or by
their first or last name. Officers of the same rank are generaUy referred to by their first name.
Officers senior to the speaker are never referred to by their first name, unless specifically
requested by the senior officer (which rarely occurs).
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tr.S. Na*id FU^t Surgeon's Manual
Conclusion
Marines are challenging, stimulating, and rewarding to work with. For a Flight Surgeon, a
Marine ^ignin^t ttspieeeilts as wide n vmt^ty of aviation and aeromedicd experience as can be
found in any command. The Marine organizational structure^ placing emphasis on strong central
command, aUows an individual's ideas the potential for far-reaching effect. An assignment to a
Fleet Marine Force is a rewarding experience a Flight Surgeon is not likely to forget.
14-8
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CHAPTER 15
SHIPBOARD MEDICINE
Seetionl: Aircraft Carrier Operations
Introduction
The Aircraft Carrier
The Medical Department
The Air Wing Flig^it Surgeon n
Summary
Section 11: Amphibious Operations
The Amphibious Forces
The Amphibious Assault Ship
Tlie Medical Departraraat
Summary
f ElfiflON Is AffiCRAFT CARRIER OPERATIONS
Introduction
While this chapter is devoted mostly to the aircraft carrier, one must reincniber Uiat it is not
the only vessel with aviation units on board. Assault ships, such as LPlP.s and LHA's, have
helicopters assigned to them for the transport and fWe support of Marine battalions ashore.
Supply vesseb and ammunition ships carry heUcopleW for VKftieitl replenishment (VERTREPS)
of other seagoing ships. The SH-2F "Sea Sprite" helicopter is aboard destroyers in a program
caUed LAMPS (Light Airborne Multipurpose System). VSTOL (Vertical and Short Take off and
Landing) aircraft are already a reality aboard the carrier and are a forerunner of the future. 1 It
is already stated national poUcy to develop smaller aircraft-carrying vessels and ?STOL aircraft
for use in the 1990'8. At first glance, this may not seem to affect health care delivery, but it
challenges the traditional concepts of carrier medicine and centralized aviation medical support.
With this glimpse of today's seagoing airarm, we turn to the aircraft carrier, which possesses
tihe largest enibarked medical department currently in the Fleet.
% 19f6, TJSS F.D. Rootevelt (CV-42) took asquadrdiiof AV-8AHawker-SiddeIy 'Tlamers^on aMedi'etrattfiar
CFinse.
15-1
U.S. Naval Flight Surgeon's Manual
The Aircraft Carrier
Mission of the Aircraft Carrier
The modern aircraft carrier, shown in Figure 15-1, has developed over a long period. At first
it was simply a slow-moving landing field for aircraft that defended itself with many guns and
some of its aircraft. During the Vietnam era, the helicopter carrier was developed as an assault
iship, using conversions of the older "straight deck" Essex-class ship. Others of these older hulls,
those which had an^ed decks, were reassigned as antisubmarine warfare (ASW) vessels
(designated CVS). With advancing space-age technology, however, these ships were found to be
too slow and to lack space for the computers and display centers needed to house ASW
components. With increasing cost-consciousness on the part of Congress and a desire to rid the
service of older ships, a decision was made to integrate the traditional larger attack carrier
(GVA). concept with Him ASW role, and the huB designation was changed back to the World
Witt n "GV." In this designation, "C" stands for carrier and "V" for heaVier-than-air aircraft
The addition of the letter "N" indicates use of nuclear-fueled propulsion units.
Figure 15-1. A port bow view of the nuclear-powered aircraft carrier
USS Nimitz, CVN-68 (U.S. Navy photograph).
Twelve of the thirteen currentiy commissioned carriers are CV's or CVN's. Virtually all
support antisubmarine warfare operations with at least otie ASW helicopter squadron and a
fixed-wing ASW s<piadrou aboard, as well as serving the more traditional roles of fleet air
defense and attack missions .^ombing). Most carrier air wings (CVW's) are configured with nine
squadrous and a detachment of photo reconnaissance aircraft. Carriers defend themselves with
Shipboard Medicine
their speed (in excess of 28 knots), with missile batteries of surface-to-surface and surface-to-air
missiles (point defense), and with the extended umbrella of carrier air wing fighters performing
barrier or force combat air patrols (BARCAP and FORECAP) at some distance from fhe ship.
Configured as an attack-ASW carrier, the various missions of the aircraft carrier become
more apparent. Conceptually, the carrier encompasses both tactical and strategic defensive and
.offensive capabilities. It can move rapidly to troubled areas wol^ldwide where no shore-based
facilities edst and estabMsli a military presence or dominance as the political situation dictates.
Offensively, it can wage conventional or nuclear wax or deter such warfare by its present* It
attracts military attention wherever it goes, thus diverting potential military offensive resources
that could be employed elsewhere. It serves as an integrating vehicle for surface warships in
company, aircraft deployed overhead, and attack submarines working below. Combining the
advantages of each of the air, surface, and subsurface capabilities, tWftate can be Ueutfdiased
quickly to both tactical and strategic advantage. This three-dimensional coverage for fleet
offense and defense, coupled with modem eteetronic hardware and software technology,
provides an unparalleled tactical and strategic capability. Because of this, it is beUeved that some
form of aircraft-carrying vessel will always exist. It may not be in the traditional mold of a
larger "super" vessel because of the cost in men and material, but rather a smaller vessel carrying
out missions similar in scope with VSTOL aircraft.
The current carrier is large. In effect, it is a city of from 2500 to 6000 persons. It sleeps,
feeds, and works the personnel 24 hours a day, seven days a week. It has from four to eight
messing facUities, three barbershops, a church, a lihrary, a iiUaU gymnasium, a 60-plus bed
hospital, makes 600,000 to 800,000 gaUons of fresh water daily, and serves as its own airfield.
The many facilities of an aircraft carrier allow it to act as a support and evacuation platform
in times of war or civU disasters. In the evacuation of Vietnam, the earthquakes in Peru, and the
floods of the Phillipines, carriers and assault ships such as the USSMduioy (CV-41) and
USS Guam (LPH-9) figured prominently in providing relief to beleaguered civiian j^pulaces.
Medical personnel assigned to aircraft carriers are tasked with the support of tiiis floating
city and aU ships in company with it. The phyMcian afloat is expected to be ready for any
eventuality. Over the history of the carrier, this requirement has resulted in an expansion of the
facilities and equipment available to the point that aircraft carriers now have the finest medical
facilities afloat
Types of Aircraft Carriers
There are five basic aircraft carrier types, as seen in Table 15-1. Size is the dhvldus
characteristic differentiating aircraft carriers; the Essex-class carriers at 31,000 torts
displacement are the smallest, so small that they cannot handle some of the aircraft in today's
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o
naval aviation inventory. The largest are the nuclear-powered, Nimitz-class carriers at
95,000 tons displacement. All aircraft carriers have the angled deck to facilitate simultaneous
laMiwiiatti mQ^f&yrfWt1md»Ay thle latter, and all have fpom two to four steam catapults. All
caniers use the Fresnel lens liuiding system and four crossdeek pendants attached to fcraking
engines for recovering aircraft. The launch and recovery ^it«in of an m&^t ewier Mows it to
accelerate a 75,000 pound object to 150 mph in 300 feet, or stop the same weight going
160 mph in 400 feet.
Table 15-1
Types of Aircraft Carriers in Active Fleet
Ctass
Ship
Tons Displacement
ESS9X
USS Lexington (CVT-1 6)
38,000
Midway
USS Midway (CV41)
USS Coral Sea (CV-43)
45,000
Forrestal
USS Forrestal (CV-59)
USSSal-atoga(CV'60)
USS Ranger (CV-61 )
USS Independence (CV-62)
USS Kittyhawk (CV-e3)
USS Constellation (C\/-64)
USS America ICV-66)
USS J. F. Kennedy (CV-67) *
78-80,000
Enterprise
USS Enterprise (CVN-65)
90,000
Nimitz
USS C. W. Nimitz (CVN-68)
PSS D. D, Elseohower (CVN-69) **
USS Vinson (CVN-70} ***
95,000
o
*Soitwtim6s contidared in a separate class,
••Dim for cornmissiorting in October 1977.
**'*ii(pected in the Fleet in 1980.
Medical Support Organization for Forces Afloat
Aircraft carriers on each coast report to their respective Type Commander (TYCOM) for
matteis that pertain to the function of the carriers themselves (Figure 15-2). On the East Coast,
this is the Commander, Naval Air Forces, Atlantic Fleet (COMNAVAIRLANT), located in
Norfolk, Virginia, who in turn reports to the Gompandef-in-Chief, Naval Forces, Atlantic Fleet
, (CINCLANTFLT), who reports to the Chief of Naval Operations (CNO). On the West Coast this
chain is similar. The Type Commander for aircraft carriers is COMNAVAIRPAC, located at
154
Opentional
When D<egfa^ (jra^s
Adminittration
Homeport
Carrier Group Commander
COMCARGRU
Carrier
Talk Group Commander
CTG
At Sea.
In Port
and at Sea
Tadc Force Commander
CTF
X
COMFIRSTFLT
COMSECONPFLT
Type Commander
COMNAVAIRLANT
COIMNAVAiRPAC
Fleet Commander
1
COMSlXTHFLTor
GOMSEVEtfrHrLT
[ nato" 1
\ Commands <
♦
i SEATO 1
Area Commar>der
1 Comma ndi i
Sixth Fleet reports to
ComnMiixler in Chief Naval
Fore^. Europe
CINCU94AVEUR
Chief of Naval Operations
^
CNO
Reel Commander
in Chief
CINCPACFLT
CINCLANTFLT
Joint Chieh of Staff
Q^^o^oiqI citain of command.
U.S. Naval Flight Surgeon's Manual
North Island, San Diego, and the Fleet Commander is CINCPACFLT, located in Hawaii. When
carrieiB deploy overseas, they leave the immediate purview of their Type Commanders, retaining
oidy an administrative fink for fiinctional purposes. The e^er laings its operational
commanaer with it, who comes from the Fleet CommattderV Staff. His title is Carrier Group
Commander (COMCARGRU), with the rank of rear admiral. When reaching the Sixth Fleet
(Mediterranean) from the East Coast or the Seventh Fleet (Pacific) from the West Coast, the
carrier group acquires other ships in company and becomes a Task Group. The senior Carrier
Group Commander, if two or more carriers are deployed in a specific fleet, is the Task Force
Commander.
The Type Commander has a Force Medical Officer on his staff who is responsible for
insuring general medical readiness of all of the carriers under the TYCOM purview. This includes
appropriate manning, equipment, supply, training, and shipboard environmental health. By
generating medical policy, ohservation Of performance, and frequent inspection, tlie Force
Medicalt Officer assists in maintaining operational readiness in the carrier force. The Force
Medical Officer also maintains haison with the Fleet Surgeon on the Fleet Commander's staff.
When deployed, the Medical Officer of a carrier is attached to the embarked flag's staff to
assist in the medical planning required to support operations for all ships in company or under
operational contiol of the Admiral. It is ifae Medical Officer's responsibihty to be aware of and
know how to use all ■ shore-basied medical facilities in his area, tiie most expeditioDB and
appropriate medical evacuation routes available in Hie area of planned operations, aU medical
personne. a.^d material available afloat, and how to best support planned operations. The
Medica. Oificer has to establish haison with shore-based medical facilities and other task force
medical assets, when available, if joint operations are planned that require medical support. This
kind of plamniing is necessary since there may be no medical liaison permanentiy assigned to the
Sixth and Seventh Fleet Staffs.
Shipboard Organisatioii
Air> f itt earners maintain the same functional organizational relationships ti-aditiond on dl
naval v.^ss,-.s. All department heads report to the Commanding Officer regarding their specific
function. They report via the Executive Officer to the Commanding Officer for administrative
matters under their cognizance. In tiie Medical Officer's case, he reports to the Commanding
Officer on ill raatters peitiaining to ifae healQi of the crew.
\s F V.. .- ^ 5-3 indicates, the snedkal department shares the same status aboard ship as the
othe.- f pij-tments. Shipboard policy and procedures are promulgated by the group of
depa-tr/.f pj: heads, aU senior naval officers. Often these men come aboard having served as
15-6
Special Anistams
Administrative
Department
Dedk
Department
Dental
D^FCment
ExeeiiltiVf Officer
Air
Department
Eng^jrieering
D^irtment
Weapons
Department
Air Wing
Commander
(When Embtarked)
Operation*
Department
I
Reactor
Departmer>t
(C^N^oniy)
Supply
Department.
Safety
Department
Marine Detachment
Chaplain
Three M Off icer
Legal Officer
MAA Force
Navigation
Depiftment
Medical
Department
CiimmurllcailOns
D^aartment
Figure 15-3, Shipboard organization chart.
U.S. Naval Flight Suigeon's Manual
squadron commanding officers or on air wing staffs. The department heads form an executive
board that advises the Command on poUcies and procedures, especially in m'atterg involving the
crew.
The senior medical officer aboard an aircraft carrier is usually a commander and is a
designated naval Flight Surgeon. He usually has had several tours, one of which has been as an
air wing Flight Surgeon. Typically, he has completed a residency in aerospace medicine and is
board certified or board eligible in preventive medicine. His title' aboiard flifp is the Medi^d
Officer, and he furictions as the senior Fligjit Surgeon.
The Medical Department
Manning
Mediciit department manpower requirements are established fhrou^ certain approximate
ratios (one physician p^ 1200 persoimel and one corpsman per 150 personnel aboard ship),
specialty Navy Enlisted Classification (NEC) needs, and the specific assignment of corpsmen and
Fhght Surgeons to the carrier air wing. For Forrestal-class carriers, the usual manning is
27 hospital corpsmen, one lieutenant Medical Service Corps (MSC) officer, and two medical
officers (the senior medical officer assisted by a board-eligible general surgeon). Table 15-2
depicts this breakdown. The third cohimn indicates the assets that the air wing brings aboard
when it is embarked.
Table 15-2
Medical Department Manning*
FOR RESTAL Class
Ship's Company Assets
NfMITZ Class
Ship's Company Assets
Air Wing TAD
Embarked Assets
Senior Medical Officer
1 CDR
1 CDR
Assistant (Vledical Officer
1 LCDR
t LCDR
2 LTor LCDR
Medical Administration Officer
1 LT
1 LT
Chief Petty Officers
2 f1 HMCS)
2 (T HMCS)
First Class Petty Officers
4
5
6
Second Class Petty Officers
6
7
5
Third Class Petty Officers
7
7
4
Non-rated Hospital Corpsmen
B
8
Total Officers
3
3
2
Total Enlisted
27
29
t5
* Based on 1 976 Manpower Authorization, peacetime complement figures.
15-8
Shipboard Medicine
Table 15-3 dtows the Navy Enlisted Classifications represented aboard an aircraft carrier.
These individuals have had specific training beyond Hospital Corps "A" school or experience in
particular duties, especially involving shipboard life. This group of permanent personnel is
augmented by squadron Hospital Corps personnel when the air wing is embarked to bring the
total number of paramedic^d technicians more into line with the needs of the ship. It is these
men who allow the medwal department of an aircraft easier to proyide its many services to the
diip.
Table 15-3
Navy Enlisted Classification Specialties in a Carrier
Medical Department (Ship's Company Only)
Title
NEC
Allowances
E-8
E-7
E-6
E-5
E-4
E-3
General Service
HMOOOO
1
1
2
3
3
9
Aerospace Medicine Technician
HM8406
1
Nuclear Medicine Technician *
HM 8407
1
Medical Services Technician
HM 8424
1
Preventive Medicine Technician
HM 8432
1
X-Ray Technician
MM 8452
1
Pharmacy Technician
HM8482
1
OR Technician
HM84S3
1
Laboratory Technician
HM 8501
1
Advanced Laboratory Technician
HM 8506
1
TOTALS
1
1
5
7
5
9
*CVNonlv
The requirements for shipboard organization are spelled out in OPNAVINST 3120.32 and in
CV SHIPINST 5400. IB. Virtually all carrier medical departments have the features required in
these instructions. Literally, a medical department is structured and operated like a miniature
naval hospital. The Medical Officer has two principal assistants. One handles administrative or
"staff" functions and the other directs the professional services or "line" functions of the
department.
Although the basic instructions governing a Table of Organization are promulgated to allow
each ship flexibihty in structuring and operating its departments, the medical departments of
most aircraft carriers organize as Figttre 154 indicates, with only minor variations. The manner
15-9
Medical
Officer
Stnior Flight
SurBeon
9»
Medkat
Administrative
Officftr
H Division Officer
Uaadlng
Chief Petty
Officer
H
Division
Training
ar)d
Education
Section
T
Assistant
iMedical
Officer
(Ship's Surgeon)
Records
and
Admin.
Section
Fiscal
and
Supply
Section
Air Wing
Flight
Surgeons
] (When emttatkidl
)■_..__
r ■■
' General
Medical
Officer
(When embarked)
Environmental
Health and
Preventive
Medicine
Section
Aviation
Medicine
Section
Clinical
Services
Section
Fignie 15-4. Medical department or^mization chart.
c
o
Shipboard Medicine
in which this organization accompUshes the mission of the department is described in
Figure 15-5, This Figure shows the functional operation of a medical department, with a
division of responsibility into seven hroad areas. The Medicfd Officer usually takes direct
supervision of environmental teahh, preventive mjedioine, md aviation medicine. The Assistant
Medical Officer supervises all clinical services and reports to the Medical Officer on performance
in these areas. The Medical Administrative Officer, assisted by the medical department's senior
enlisted man, manages and supervises all of the departmental support functions.
Figure 15-5 is also useful because it describes flie extiealt W jnyplyenient of the medical
department in the daily routine of the |hip.
Facilities
Figure 15-6 shoitvs a cannier profile and thelocartion of the rae&al department aboard ship.
On most carriers it is on the second deck, just below the hangd^ deck {main deck), between
frames 90 and 120. Access issfrom tiie port or starboar4 side.
Eiguie 15-7 dfeplcts the fcaac layout M a Hiittfi^-eTlasi medie^ d^iartment, showing the
location of the various treatment and supporting spaces. Forrestal- and Enterprise-class carriers
have two wards with the advantage of using a specific area for sick call screening. Nimitz-c'ass
uses the physical examination area for sick call screening and schedules all physical
examinations, eye, and ENT clinics after sick call is secured. The advjttitages of the Ninaitz-class
layout are size, privacy, ahd C6iii|itl6te ttccesitsOjat^L Oiier notj&le features of tiie Nimilz-elass
carrier are the spacious surgical suite and the intensive care unit (ICU). The ICU has been
retrofitted on Forrestal-class ships in recent years. Figures 15-8 to 15-12 show the medical
examination room, the operating room, the medical x-ray room, the inter sive care unit, and the
Wfclical laboratory; aboard the tfSS Mmtlg. F^res 1543 1544 stiow the dental x-ray and
OfperatingrooffisioniMs^ship. !
Figure 15-6 shows six dispersed and peripherally located "aid statiors" on aircraft carriers
called Battle Dressing Stations (BDS). When the ship is in Readiness Condition I {General
Quarters), and aH harids are at "Battie Stations," fte ship is entirely closed. All water-tight doors
are secured in order to enhance the ship's survivability. This can make casualty movement a
tedious and difficult process. In order to avoid unnecessary delays in the primary treatment of
injured personnel, these Battle Dressing Stations are manned by physicians, dentists, and
corpsnien so that casualties occuning within their areas of req)onsibility can be given primary
emergency care until movement to the main sickbay can be effected.
A major advantage of the Battle Dressing Station concept is that it allows the dispersion of
medical pasonnel and equipment around the ship. Should one .area of the ship be damaged with
a loss of medical assets, 1het#-sf© are more available to cairy oii the, job.
15-11
Adminiftmive Snvien
PrtrfmioiMl SmicM
H DtVlSION
TRAINING AND
EDUCATION
SECTION
Leading Petty
Officer {L.P.O.)
Damage Control
Petty Officar (OCPO)
H Division
Training P.O,
aifpboatd
I 1 Biriing r.U,
3M Coordinator
Human Goals Rep.
Command Training
Team P.O,
Career CounMlor
Damage Control
P.Q.S.
Drug Exemption
RaprwetiuilM
3M P.Q.S.
H Diviiion Sect
Leaden
Medical Depart.
P,QJ5-
Watch Quarter
Stal^BIII
Corptman Eval.
Board
H Divitlon
SatatyP.O.
Medical Dapt.
Library
Explanttory Notet
3M — Material MaintenarKe Man u ga i iwwt
PRP - Paraoniwl RalipbWty PrppMn
PCS — Pttnonnel dualtilt^oh Standardbatioti
ADMINISTRATION
AND RECORDS
SECTtON
FISCAL AND
SUPPLY SECTION
Praperty
Adminittfative
Aaittance
Budget Planning
Medkal RacoRh
Radiation
Healtfi Program
Accounting
Procurement
ManiKfHaant
PRP Program
Contultationi
and Raferrais
Other Procurement
and Open Purchase
Emergency Care
Billing
Stock
Management
Inturance
Inqulriei
Pereonal
Emerge rwy
Equipment
Invmtory
CHAMPUS
Advisory
Medical
Equipment
Planned
Maintaiwica
Syitnn
MEDEVAC - i
Cdioidihaior
Mail Courier
Cdmmunleationt
Coordlnatibn
ENVIRONME^TTAL
HEALTH AND
PREVENTIVE
MEDICINE SECTION
Shipboard
Sanitation
Program
Shipboard
Potable Water
Monitoring
Pen and Rodiht
Control Program
Shipboard
Toxicology and
Hazardous Maftriaii
Program
VD CwKroi Ptagam
TB Control Program
Immuniiatjon Program
Heat Strati
Piavention Pronwrn
Hearing Conservation
Communicable Disease
Monitorinn Pronram
Non-Ionizing Radiation
-Penonnel Exp. Survey
AVIATION
MEDICINE
SECTION
CLINICAL
SERVICES
SECTION
Physical Exams
Sick Call
Eye Clinic
Emergency and
Treatment Room
ENT Clinic
Audiology
Surgical Preparation
and OpstwtirVjRpfimc
Sight Safety
Program
Wetght Control
Proflram
IMBdicdVKMd
Aviation
Medicine
Intensive Care Unit
Aircraft
Accident
Investigation
Team
Pharmacy
Laboratory
X-ray
Flight Deck
Team
Phyticih«|l|)y
SAR Retponie
Team
Decontamtn8i§in Tom
MEDEVAC
Escort Team
Madicat Raspoma laam
Figure 15-5. Functional ^^am of medical department organization and services.
o
Aft Auxiliary Battle
Dressing ^tion
Forward Auxiliary
Battle Dressing
Station
Sickbay
04 Flight Deck
03
02
Livml.
idships /Mjxiliary Battle
Dressing Station
(Flight Deck BDS)
TT
loi
- 1
-2
7.
Level
Laval (Hanoar Dwk)
LBval (Saeond Deck)
Aft Banle Drestinn
Station
Main Battle Dressing
Station
Forward Battie Dresting
Statiim
Figure 15-6. IxK»tion o£ nie#»|l 8pi^^!ib|MA m
Crew MRwroom
& Wpnt Any Arsa ,
USWpni
EIbv No 2
Cr««WR,WC,SH;
Decon Sta #2
Mad Su m
■ccwi Trk| /
Fwd PRPLN
Load Ctr
Swed
Rm No 4
Acft
Wpns
Cont Svs
Comptr
Rm
////
Fit Surgeon Off _.
Consult Rm^--
SD Off
AVN&STORBSjD^t
AccewTrk-
'vtttI Med I Msd Y/^^J^^^
J ScmtjRm
Apparatus Rm
Supply Dapt
Off
(Admin)
Quiet Rm
#2 Bath
Pub Info Off
Dark Rm
Craw Galley No 1
Figure 15-7. Medical depwtment of a Nimitz-claBs carrier.
o
SMpboard Medicine
Figure 15-9. The operating room of the USS Nimitg, CVN-68
(D.S. Navy photQ^aph),
)
15-15
U.S. Naval FU^ Surgeonis Manual
Figure 15-10. The medical x-ray room of the USS Nimitz, CVN-68
Fi£urt 1.1-11, The medical quiet room (intensive care unit) of the USS Nimitz, CVN-68
(U.S. Nssy photograph).
15-16
n
Shipboard Medicine
Figure 15-13. The dental x-ray room of the USS Nimitz, GVN-68
(U.S. Navy photograph).
15-17
U.S. Naval Fli^t Surgeon's Manual
F^ure 15-14, The dental operating room of the USS JVimifcr,CVN-68
■ (Ij.S. Navy photograph).
Mission and Capabilities of the Carrier lAedi^ill Departinent
The Carrier Environment. The intehsity of carrier <^eratioiis, with the 24-hour a day pace
of launching and recovering aircraft while at the same time operating the carrier itself, combined
with the ongoing need to feed and berth the crew, places heavy burdens on manpower and
materials. Good hygiene and general cleanliness are hard to maintain and must be addressed
constantly. Toxicological threats abound over the ship, and there are a thousand ways to be
injured in the hazards of working areas. There are 2600 spaces on ait aircraft carrier designed for
general living, sleeping, eating office WQt^ maintenance and storage of equipment, heavy
machinery, and computers. Much heat is piduced that has to be dis^pated or vented to the
exterior; noise levels can be generated that must be isolated or protected against. Thousands of
miles of cables, wiring, and piping provide power and services to all areas of the ship. Massive
stores of several kinds of fuel, ordnance, and other combustibles are maintained. In effect, the
functions of an industrial city with a military airfield are crammed into 32,525,000 cubic feet.
In every area of operation in this floating city, the medical department has some interest and
fimction. The medical department mission in this changing and demanding mvironment sounds
deceptively simple, however, — to support aU functions of the ship by providing medical care to
the sick and injured, to insure the health and weU being of the crew, and to provide relief and
assistance to military and civihan personnel when required and as the Commanding Officer may
direct.
Implementation of this mission is an endless and demanding task. The next sections describe
the manner in which the functional requirements of this task are met.
Clinical Services. Direct patient care is the most obvious fiinotion of &e tnietidM£ department
in the execution of its mission. Sick call is the initial point of entry into the health care function
of Ibe medical department. Next come the emei^ency room and the various outpatient clinics
and services. Inpatient services include the ward, intensive care unit, and operating room
functions. This is the "hospital" function of a carrier medical department and the one which
requires constant attention to insure the highest quality health care. Many nursing functions
have to«be assumed b^ic0r{)sni^ so an intensive innemce^aimng program is necessitry M inWil^
that qualified feirsoaaidi do this work. This is becoming increasin^y difficult as more
sophisticated equipment i$'b@ii]@ placed in a cand^ lUedical departn^t. ■
Table 15-4 depicts in summary fashion the patient care services and facilities available in a
carrier medical department.
Table 15-4
Direct Patienji Care ; ••
Facilities
^ ^ '■ ilix 1
Clinics and Services , j
Physical Exam Center
Sick Call
Wei^t Control Clinic
Consultation Rooms (4)
Blood Pressure Clinic
Emergency Room
Eye Clinic
Surgical Suite
ENT Clinic/ Audiometry
yVard ,.
Minor Surgery Clinic
tsolation Rooms
Physiotherapy
Intensive Care Unit
Interview/Counselling Clinic
Wet and Dry Physiotherapy
Venereal Disease Clinic
X-Ray
Physical Examinations
Laboratory
' Inpatient Care
Pharma<^'
' (1) General Medical Care
(2) General Surgical Care
Environmental Health and Preventive Medicine. With the advent of the Occupational Safely
and Health Act of 1970, the preventive role in shipboard medicine has grown in visibility.
Although a major concern aboard ship has always been the prevention of disease and injury, it is
15-19
U.S. Naval Hi^t Smg^Qu'sMaiiual
only recently that proper emphasis has been given to this topic. The traditional practice of
shipboard medicine emphasizes the sanitation and hygiene aspects of a preventive medicine
program. This includes potable water analysis, food service procedures monitoring, and venereal
Siii|Qe.(i9fiO) hearing conservation and. heat streSitprevention have become quite important
and are now operated as separate programs. Chapter 8, Otorhinolaryngology , describes the
operation of a hearing conservation program. The need for base line and reference audiometries
on all active duty military personnel is mandated, and careful follow-up must be maintained.
This trsnslates into approximately one audiogram for each mm ahofffd ship per year (6000
audiogram^ for a Nimitz-class vessel). The logistics of diis and audiometric booth certification
are itnj^osing. By directionjveacb of tJae audiograms must be frniaaually derived examination, so
that up to 6000 manual audiograms, as well as the issuance of ear plugs and instructions, must
be effected for a meaningful program. i i
Heat stress has been a problem aboard naval vessels mice liie days of sail. Adequate
ventilation and proper environmental temperatttJfie control have not been possible in even the
best spaces until the past ten years. Habitability, as an effective program, did not officially exist
until the beginning of this decade. Like noise, controlling heat at its source always is the desired
approach, but this usually takes expensive and time-consuming retrofitting. A monitoring
program using the Wet Bulb Globe Temperature Index has been developed to identify and
concentrate on areas of potetttial heat stress. Using these data and physiological limit tables,
"stay times" for work can be devised to protect the watchstanders in these spaces. Heat stress is
discussed in more detail in CShapter fl, ITiirmai Stress andf /n^^ries.
One area that has not received systematic attention in preventive medicine is the hazardous
materials monitoring program. A vessel of the size and complexity of an aircraft carrier has
many operations requiring the use of known toxic or hazardous mat0llifib. T%fe wMcBng of zinc
alloys, cleansing of boilers y0a. tplaolj ^try into JP-S tanks foi- ddaning, l&ttr^ of aircraft
with Turco, use of halogenated hydrocaJ'bons, asbestos laggir^ in all but the newest ships, and
liquefied oxygen system maintenance are just a few of the many routine daily exposures to
hazardous agents. The need for constant awareness, supervision, and training of persormel using
these materials is obvious. Medical departments afloat must keep track of the chemical agents
{^oard, as well as the toxicology of these substances. Chapter 22, Toxicology, deals with this
subject in greater depth. -is
Training Functions. A medical dep^ment haB a training commitment to the diip and to
itself. Damage Control Personnel QuaUfications Standardization (PQS) requires a certain level of
15-20
!c. _ Shipboard Medicine
expertise in first aid on the part" of' all crewmen. This requires divisional training on a scheduled
basis using corpsmen as instructors and unscheduled training of litter bearers and repair party
personnel during General Quarters drills. Shipwide training in the treatment of electric shock,
^oke inhalation, heat stress prevention, hearing conservation, and sight safety is now rei^ie$d
l^pe CQm]nMid|^c& and isrinclmded M the; Meet Tistiniiig 0r@up review of the «d«ij^irey ijtf
mBMial is. common for an airellaft qiuniar to sehedille 300 iftan-hourf of
trp^ngrK^iA; ^eseitf^pii ^MW^^shi 0petAMyb0mm an< extendedilepltsymbiife
There must be a comprehensive corpsman training program to insure that competent and
cjirrently qualified persormel are manning the miidieal deptrteent.'^aliflealidftsiliffivf(& Mffl
established for thirty-flv© priMiajy'r|ato8 and five seeondaif^ speeialties* The jobs cover sueh
diverse activities as sick call, lifeboat duty, rescue and assistance detail, repair party, audiogram
technician, physiotherapy (including cast application), and intensive care unit nursing. The idea
of this "PQS" program is to insure that only qualified people perform specific tasks. To sustain
such a program requires ten hours of instruction per man per week. To insure competency and
continuity in specific assignments, personnel should be rotated among the various work centers
Yjthin tljj<p,.jde|»artment. This rotation policy includes corpsmen witjj, specialty NEC's.. The
4iyerjS!e^,tr^B}jpg t» corpsman recwes will benefit him and his fixture commands. . , , , . .
Casualty Management and Disaster Support. Aircraft carriers by their very nature present
potential hazards to the personnel who operate them. In recent history, USS Enterprise,
USS Forrestali and USS Oriskany have experienced major conflagrations involving the upper
decks. Since such events are possible, every aircjaft carrier, must have a workable and well-drilled
mass casualty plan. This plan mn^ addi«® the physical layout of the slup, Hhe ckmx^MfMm
ship during General Quarters, the distribution of men and supplies, and the location of the
accident or incident aboard ship. Concepts of triage and walking blood banks have to be
understood by aU. The plans must be flexible enough to withstand the loss of medical
department spaces and personnel and to lend aid in the event of a disaster occurring on another
vessel or ashore. In 1975, when the USS Belknap collided with the USS Kmnidy both things
happened. Main sickbay had to be evacuated while oamt^ties from the USS Belfenap were
r^|!dyeid for iidtial treatment and fprthef^ evacuation.
Patient Transfer and Medical Evacuation. As a primary care facility, often supporting a
population of 10,000 aboard and on ships in company, an aircraft carrier is frequently utilized
as a receiving h,q^pital and as a transferring facility for hospitals ashore. No two medical
©V^uiittaiEjfviaiie jjifjrpaiij^* 15ii|?iJ^ic pi^^ are the amie, however,, j|nd are chscussed in
Chapter 17, AeramnM^d $vm^^ff^ T^^ ^vmm^n a* ^ck and injured personnel is an "art."
Frequently, the physician is attempting to anticipate the occurrence of a pathophysiological
15-21
U.S. Nw^ Eti^t Swge6n% Maiiuat
event by several hours. If he waits too long, evacuation may be impoaefflfl#!iiKlB|i not wait
at all and evacuates the patient peremptorily, there may not have been a need to evacuate and
the patient arrives ashore a well man. Judgement, caution, perception, and patience are
mandatory. Often, however, geographical location,, time of day, weather, or ship's mission
@@inl]S^^mt makes the decision fi» «)ibE^ip%fi&i£alt J^^Jth^^
ipirivent evaCu«dlon^ whioh e^plianii Ae ^sciflei&tciiiedical facflitis^it^^ffflld^abfed canHers.
Constant awareness of ship's location, the weather, the ship's mission, and the aviation assets
available for patient transfer are required to successfully coordinate a medical evacuation. When
deployed overseas, it is imperative to know aU of the details of the Air Force Medical Evacuation
System, fdlied bealth cstfiB facilities^ai^OFei^ and bdW ta me them to the patient's best advantage.
Buidng the course of a normal cruise, such piepifrdtion altd planning will be useful on m^^ttto
one occasion. ■ ; . Vu; ,ftr ./.r^ - sd ; jj-.
ITie Cruise Cycle
It is hard to describe a"typical" cycle since the end of the Vietnam conflict. Basically, all
diips go through such a cycle once every 18 to 24 months. A good starting point in describing
Ihe c^clfe is the yard period (either major overhaul or post-cruise maintenance). The air wing
disertibarks after a cruise and returns to %ts Vdiloas'homeportd^^i^dinme^be a stf^HKBlM' £^
then retraining period. Figure 15-15 #tows the schedule for the ship and air wing in parallel in a
typical cycle. The at-sea periods vary after Operational Readiness Inspections before a cruise is
scheduled, depending on whether or not there are fleet exercises or "mini "-cruises to be
accomplished. Planning for personnel training, leave, supply acquisition, and specialty patient
referrals is a constant problem during the cruise cycle, requiring much of the physician's time
atid effort.
The Air Wing Fhght Surgwa
Duties and Responsibilities
The air wing Flight Surgeon is responsible for providing the Air Wing Commander and
squadron commanding offlcers with staff expertise on the physical and psychological aspects of
aviation and serving as a repository of informa^k 6n physlblogical stre^. Each air wing usuaUy
has billets for two Flight Surgeons. Air wing components are homeported at Cecil Field,
Jacksonville, Florida (East Coast attack squadron), Oceana Naval Air Station, Oceana, Virginia
(East Coast fighter and heavy attack squadrons), Naval Air Station, Miramar, California (West
Coast fighter squadrons), and Naval Air Station, Lemoore, California (West Coast attack
l^fdtom), as shoWn in Table l^^S. This represents a "b|^44Qading" concept which plAbes
aaiiatait ttf a given type at a particular base itit eim of truniiig sind miintetiance. '
15-22
Shipb,Q<unl Medicine
Ship
Air Wing
Shipyard (3 Months)
Sea Trials (10 Days)
Flight Deck Certifiea^on
,61.-1 vv'-^
Fleet Refresher framing (319 Days)
Air Wing Carrier Qualifications
Weapons Training
11,
Maintenance and
Upkeep Inport'i 10-30 Days)
Type Training Periods (3 Months)
At Sea/lnport
Carrier Qualifications
■If . .
Operational
Readiness
Evaluation (3 Days)
Preventive Overhaul
and Maintenance Periqd
(10 to 30 Days)
Cruise (6 Months)
Detachment
Aboard
<
Move Aboard
Ship
r
iifi^iie Aboiird
Ship
Homeports
Training Period
Weapons Deployment
Retum Home
J
Return Home
Stay Alioinl Ship
Figure 15-15. The ship/air wing cruise cyde.
15-23
U.S. Naval Flight Surgeon's Manual
Table 15-5
CV Carrier Air Wing
Aircraft
Squadrons
East Coast
West Coast
F-14A
Tomcat
2
Oceana
Miramar
A-7E
Corsair V.
2
Cecil Field
Lemoore
A-6E
Intruder
1
Oceana
Whtdby Island
EA-6B
Prowler
1
Whidby Island
E-2C
Hawkeye
1
Norfolk
Lemoore
SH-3
Sea Knight
1
Jacksonville
Miramar
S-3A
Viking
1
Jacksor>ville
Miratnar
RF-8
Crusader
Detachment
iWiramar
A second responsibility for the air wing Fl^t Surgeon is to possess a working knowledge of
the aircraft in which "his" aircrews fly in order to better assess the problems of the
man-machine interface. This knowledge becomes vital both in reconstructing the events
surrounding' an aircraift incident or accident and in preventing future similar occurrences.
A third responsibility is to serve as a physician in the naval medicd Cfire i^stem. This is
difficult sometimes since in his role as an air wing staff member a Flight Sui^eon is not assigned
to a specific medical facility. Wherever he goes, his medical function is as temporary additional
duty. Aboard ship, he is part of the ship's medical department but still retains his
responsibilities to the Air Wing Commander. At home, he reports to &e local dispensary for
additional duty but is required to spend productive time with the air wing staff as well. The
Flight Surgeon utilizes the medical facilities to render medical care wherever he goes and has the
additional requirement of maintaining close contact with his parent organization.
Assignments Ashore
The air wing Flight Surgeon is absorbed into the medical facihties at home port to assist in
handUng the increased work load his units place on the local health care system. This is usually
at the regional branch dispensary. While at home and between cruise cycles, the Fhght Surgeon
has much to dp to prepare for the forthcoming cruise. Medical problems need foUow-up,
innnunizations need updating, refresher survival and physiological training are required, training
topics for squadrons need preparation, and the Flight Surgeon's own professional development
requires attention. Type Commanders recommend that air wing Flight Surgeons receive four to
eight weeks of anesthesia refresher training in order to be better prepared to assist the Ship's
Surgeon when deployed.
Shipboard Medicine
Assignments Aboard
When the air wing embarks, its Fhght Surgeons report to the carrier Medical Officer for duty
(temporary). It is CltoJ»ft f^KcMe© to'<§®ip tbeliS m ttffff of H^teh it!a»fe'i4feivfel^ fo^^iM®'fl#f
are held ptofespoa#y'^*^^E»nsffiile. Sidk caU^ the physical examiiiation cseriter, EENT cHnic,
preventive iQfiiS0|i>ie, and aviation medicine are the usual areas of assignment. This enhances the
marriage of ship's company and air wing personnel into one functional unit. The corpsmen are
similarly absorbed. Workload, watches, and stations during various emergency biUs are shared
equally. There is some free time for recreation and other time to attend to air wing matters. The
work commenced at hesiJie ilit6«ilifi'ii»^ltd>8hip and cotttinues unabatfed.
As type-training nears completion, there are myriads of professional and personal details
that require attention before the cruise commences. The ship is in port and the air wing returns
home. Hearing tests, immunizations, physical examinations, and supply lists have to be
completed in the remaining few weeks. Leave with the family is always desirable, but sometimes
difficult to arrange. The list is endless and requires much attention. The ship leaves on Schedlde
whether the individual is ready or not, so planning is a must. Most ships publish a deploymafit
schedule to assist in planning milestones. Type Commanders also publish a check list for
accomplishment prior to commettcu^ an extended deployment (CNALINST 6000. lA).
Professionally, the cruise is much more rewarding if the air wing Flight Surgeon is organized and
prepares for it carefully.
Summary
In the memory of most Navy Flight Surgeons, there resides a special place for their
experiences aboard an aircraft carrier. Since World War II, the carrier has represented the
epitome of what naval aviation is all about. Medically, it is unique among naval medical facilities
and is becoming even more so with the newer carriers. The past 40 years have seen
development of the carrier niedieal department from a small "sickbay" to a medical and surgical
hospital with more than 60 beds. It has its own medical and surgical intensive care facilities
complete with volume respiratory support and monitoring equipment.
What makes a earner unique in medical experience is its intense, demanding envirotunint
coupled with its, mission. Routine operations are constantly highlighted tvith an aura of tWc.
The carrier's mission carries it to the forefront of national policy, especially in troubled areas.
Its existence always impHes the potential for danger and demands perfection, professionalism,
and constant vigilance. Serving vnth a medical department aboard the largest warships afloat
places a physician in the front of what is happening in the world, on his own, with no one else
1525
U.S. Naval Flight Surgeon's Manual
immediately available to assist him in making decisions or treating patients. Causing a huge
warship to deviate several hundred miles from its assigned mission in order to execute a rescue
:f%#ftl?Wt^ ^ itt4ividhial ajshore for definitiye mettitpl t^a^fi^ ^m m^Me concept, but
i^^llfttalfin the decision-making process regarding patien^^
The routine daily medical ministrations aboard a carrier bring a close association with the
finest and most talented professionals in the world - the naval aviator, his aircrew, and all the
personnel whose efforts allow man to fly from a ship at sea. To work with these people is a
satisfying experience, and to fly with them, an iaete4Pl& pleasure, lo sharie th# boredom of
long at-sea periods, the sadness of family separation, file relief and joy of a liberty port, the
gladness of a return home from a cruise - these are things that cannot be described nor
appreciated by the uninitiated. All of this, together with practicing a rewarding subspecialty in
medicine is what makes carrier medicine the satisfying experience and great challenge that it is.
f <
• s
15-26
Shipboai^ Medicine
( ^
SECTION n: AMPHIBIOUS OPERATIONS
4
The AmpJiibious Forces
The Navy's amphibious fprpps, of which the LPH is a pRrt, ate tasked with moving troops,
equipment, and supplies from sea to shore in order to secure a desired objective. The term
amphibious derives from two Greek roots, i.e., "amphi ," meaning "on both sides" and "bios,"
meaning "Ufe". The classic symbol of the amphibious forces has been the alhgator, a
characteristicfilly fearless feflow, very well adapted to "living on both sides."
Relatively recent changes in naval ship designations have given the letter L (landing) to all
vessels of the amphibious forces. Several types of amphibious ships have evolved over the years,
each uniquely configured and suited to its own particular role in the tremendous complexity of
an opposed assault from the sea. Examples of amphibious ships are ^ven m Table 15-6,
Table 15-6
Ship Types orfhe'Atej^Mbioaa Force
. « , Type
Designation
Tons Displacement
Inshore Fire Support Ship
LFR
7,000
Tank Lpudi^ Ship
LST
7^00
AmphJ^Mjus Qmm^ syp
LCC
10,500
Amphibious Cargo Ship
LKA
10,600
Amphibious Transport Ship
LPA
20,600
Dock Landing Ship
LSD
11,500
Amphibious Transport Docic
LPD
17.000
Arrtpffiblf us Assault Ship
LPH
18,000
General Purpose A»aultShip*
LHA
1 40,000
*Verv recently developed and hlghiv automated:
It is probably safe to say that no sea-going community contains as many varied ship types
and individual missions as the Navy amphibious forces. . - ^ .
Formerly one of eight Fleet-type commands (TYCOM), the amphibious forces are now
comhtoed with the destroyer, service, and mine forces, as shown in Table 15-7, into large
consoUdated TYCOM's, Commander Naval Surface Forces Atlantic (SURFLANT) and Pacific
(SURFPAC). Like the major carrier, submarine, and FMF TYCOMS, SURFLANT and
SURFPAC report directly to their respective Fleet Commanders (see Figure 15-2), who in turn
report directly to the Chief of Naval Operations.
' )
15^27
IJ.S, Naval Flight Surgeon's Manual
Table 15-7
Fleet Type Commands
Amphibious Forces
Cruiser — Destroyer Foraes
Service Forces
Surface Forces
•■ w. 'I-
IVIine Forces
Fleet iVIarine Forces
1 -
Fleet IVIarine Forces
Naval Air Forces
Naval Air Forces
Submarine Forces
Submarine Forces
Training Commands
The Amphibious Assault Ship .
The amphibious assault ship (LPH) (Figure 15-16) is, in every sense, an aircraft carrier; there
are more similarities than differences between this ship type and the more familiar CV types.
Basic to both is their primary mission of transporting, launching, recovering, and maintaining
their particul» idreraft mix in ordef%> accompHdi the objective ailfaiid. ©flier ship types carry
aiecra:^ to be sure, however, their primary misgisns revolve atrCiirid other tajsks, aria Aeir aircraft
are used only in a supporting or wixiliary role. Far from being suppdrfing or auiiUary, a carrier's
embarked aircraft are its very reason for existence.
Figure 15-16, The at^hibioas aasault diip USS Giiamj LPHt9 1 „ (? >ijj o: / r
(U.S. Navy phot^t^h).
lSi28
Shipboard Medicine '
n
The rapid development of helicopter technology and capability since World War 11 has been
the T^mimsy stteute td; Urn ^^<^mmtk 0$r^&i ^phiiite as8aiill»#i^'?illso llns^
colloquially m fi^hslie^^terthasault 'ship" oh« '^h^eopter 'eapderi'^ ^Phe i^ibfeeipt irf'
envelopment from the sea is of tremendous importance in amphibious opMitions becWse
!• airborne troops are not dependent upon favorable beaches (unfavorable ones were
responsible for horrendous casualties at Tarawa and in certain sectors of the Normandy
landings)
2. the landing force can become established ashore more quickly
3. more dispersal of the landing force is feasible, thus ehminating large concentrations of
men and equipment on the landing beach.
The first ships to ediifi^fed foif fliis amphibious a^ailtt role ^etfe l^orld War B vintage,
Essex-class carriers, none of which is currenlJy used in this ihsAkm^ Iti adiBtion to various deck,
weapons spaces, and aircraft maintenance modifications, accoiMmodations for a Marine
Battalion Landing Team of 1500 men were made. So successful was the LPH concept, in
training exercises as well as in several contingency operations, that a new ship type was
specifically designed to support this assault concept.
As Table 15-8 shows, the newer LPHs, Usted in Table 15-9, are approximately one-half the
size of their Essex-class predecessors. Present doctrine caUs for the deployment of the Battalion
^ ^ Landing Team of 1500 men, one full squadron of Marine transport helicopters (12 to 15
CH-46's), and smaller detachments of heavy transports (3 GH-53's) and gunships (3 to 4 AH-l's)
for the usual amphibious exercise. „ ,
Table 15-8
Comparison of Essex-Class CV with Iwo Jima-Class LPH
EssM
Iwo Jima
Disptacemsnt, TjE^n^ ,
40,600 ;
18,000 ]-'.
Length
em
602
Beam
202
84
Draft
31
29 ' .
Shaft H. P.
150,000
22,000 < 7
3,200
2,500.
A major difference in newer LPK design has been a quantum leap in medical capability.
Wherpjm Ae Iss^XHelftss GV's had a hospitd bed capiacify of jpproximatsdy §10,. and today's
Nimitz-class CV's have 60-I-, the modern LPH boasts a modem, well-equipped hospital vvith
contiguous expansion capability of approximately 150 beds and all of the medical support
)
15-29
U.S. Naval Flight Surgeon's Manual
^piibUity of the largest CV. This unusually large capability in a diip of relatively small size is
d^^M ii. Mi^,,imt^0w& ^VaE^^^em helicopter capability^ the rapid airborne ing^rtieM of Si
bm^mg^jrce and the equally rapid aifijgvjtmation of haltle citiaiil3^l«aa been combat-proven
and, in effect, mandates a secondary role of "mini-hospital-ship" to the LPH.
Table 15-9
LPH's in Commision
Atlantic
Pacific
USS Iwo Jima (LPH-2)
USS Okinawa (LPH-3)
USS Guadalcanal (LPK-7)
USS Tripoli (LPH-10)
USS GuaiTi (LPH-9)
USS New Orleans (1,PH-11)
. USS Inchon (LPH-t?)
Shipboard organization in the LPH community is essentially the same as that described for
aircraft carriers. The medical support organization for forces afloat is a very close parallel,
excepting the names of the respective TYCOM's.
An important organizational difference exists, however, in the relationship of the LPH and
her embarked units. The commanding officers of the Marine BLT and helicopter squadron (and
olitei> deCaehinents) report to the Landing Force Coinmander, a senior Marine officer of colonel
or flag rank, depending upon the size of the operation. Again dj^ndmg upon tfie iize and
disposition of the operation, the Landing Force Commander may be aboard the LPH or another
ship of the Amphibious Task Group. He, in turn, reports to the Task Group or Task Force
Commander, a naval command, until the Landing Force is disembarked.
The Medical Department
The LPH medical departnient organization and facilities are essentially the same as
previously described for the CV'a wiiS a few exceptions.
First, and of foremost importance, LPH's at this time have no permanently assigned medical
officer. When no embarked units are present, the department is headed by an HMCS or HMC.
NonnaBy, there are two chifcfs and approximately 15 hospital corpsmien of various NEC's. If a
dental officer is assigned, he is responsible for supervising die medical department.
Only when an LPH deploys is a medical officer assigned. This uses the so-called "Fleet Pool"
Cpticept, in which physicians ^om major hospitals are assigned for periods of tiiree months at a
ttoe. Some of tfa^ hsive hiA Mh^f^^ timMg m& ^tae have not.
15-30
Shipboard Medicine
Currently, the embarked helicopter squadron brings aboard a Flight Surgeon from its parent
Marine Aircraft Group. He is primarily responsible foB^e-iierittoftiKal support of embarked stfr
unite and normally remains with them for ^ dtar«#ttl of j|(«i6w4se i^m m^im^^)- He%
generally accompanied by one or two corp^en. His relationship in thf .oyierrt 4tpte5lt5ijSi|t
scheme is exactly .tjiat of his CY.c^Uieagiie., .y .... . ,.i .m l .
The Marine BLT presently embarks with approximately 12 to 15 corpsmen. During at-sefi
periods, these corpsmen work in the medical department, although tiipfJ^mim an J^egcid^]^!^
of their battalion and wiU accompany it during any real or simulated assault.
■ ''I
During actual combat or major disaster relief operations, the medical department is further
augmented by additional squadron and BLT corpsmen, bringing them up to T.O. strength of 3
and 50 respectively. Additionally, two medical officers will join the BLT. Finally, a
predesignated surgical team (Table 15-10) from a major naval hospital will embark with an
ample sup|% of oqftsumable material, thus fully staffing the LPH's well-de^gne4 ipiiet.. .■
Table 1540
Composition of a Surgical Team
1 General Surgeon
1 Orthopedic Surgeon
1 Anesthesiologist
1 Medical Administration Officer
1 Nurse Anesthetist
1 Operating Hoom Nu rse
1 general ^ry ice Hospital Corpsman
t Clihieal LabTechnician
1 MedlBal Sei^ice technician (HMC)
1 X-ray Technician (HMC or HiVIl)
5 Operating Room Teclinicians
T Orthopedic Cast Room Technician
^ce the LPH is intended ti? support as well as to deploy its BLT, the medical spaces have
been designed specifically to receive and treat large numbers of battle casualties. In addition to
the wide passageways present in the larger CV types, the LPH boasts several unique attributes.
There are two fuUy equipped operating suites and a minor surgery area which can be quickly
rigged to handle major cases. Full blood banking facilities are capable of processing large
volumes raplilly. Sevieral ,in1:eimve care l^ds are avalUible with full monitoring/life support
ci^ajbi^l^. Tlie fixesi 80-bed ward is continuous with troop berthing spaces allowing immedi|1;e
expansion to a full-bed capacity of 150+. ^. ,^
15-31
U.S. Naval Flight Surgeon's Manual
When actual casualties are inbound, designated litter handling teams are called away to the
flight deck where they are met by the Triage Officer (normally the Flight Surgeon). As he enters
fydisaiMM^ Ms teams, the Triage Officer begins the sortiflg process wMfeh'cantinues, ivilh
Mquenf t#vMon^, fHe didk^^ige elevator and thert down to the easualfy htfldittf £ffiea iaft ftf
the hangar deck. From this holding area, where emergency treatment is begun, patients are
selectively brought by a special "patient" elevator to the medical department spaces on the
01 level, immediately above. Thus, casualties are moved rapidly, and entry into medical spaces is
rigidly controlled so as to maximize the quality of care for the greatest number.
Many teams have found it advantageous to rotate medical officers' responsibilities on
different days of an operation, within obvious limits. Thus, each officer is able to view the
operation from different vantage points. During such an operation, the Flight Surgeon is sure to
find ample opportunity to hone his surgical skill under well-qualified supervision.
Major disaster relief operations provide yet another excitiiQg and rewarding oppctftunity for
the LPH and her embarked aircraft to serve the national interest in a wholly diffepent manner. It
is difficult to imagine a vessel more ideally snited for this particular task than the LPH or the
newer LHA.
Summary
Assignment to an LPH-deployed helicopter squadron provides a Flight Surgeon with a
unique opportunity to participate in some of the most varied and demanding aviation activities
found anywhere. Modern helicopters lend themselves to a multitude of missions, e.g., troop
transport, resupply, medical evacuation, search and rescue, air reconnaissance or recon team
insertion/extraction, underway vertical replenishment, aircraft/equipment recovery, attack and
fire suppression, and so on.
The helicopter, with its impressive capabilities, has brought the Flight Surgeon into the
amphibious forces; present as well as future developments are certain to keep him there. The
new 4O,0OO ton- general purpose assault ships (LHA) (Figure 15-17), of which three are nowin
commission, promise to far outstrip the LPH in terms of aircraft handling ability, not to
mention the carrying of troops, cargo, and heavy assault vehicles, and casualty care. The advent
of VSTOL aircraft and their recent trial deployments aboard amphibious force ships adds a
whole new dimension to this rapidly evolving fleet capability. Current interest in smaller CV
types for future attack and antisubmarine forces will strengthen the fledgling union between the
VSTOL community and the amphibious forces. The decommissioning of the Navy's last active
hoi^ijtal ship has left a void that, by default, must be filled by the superb medical capabilities of
the LPH/LHA. Finally, the steady decrease in U.S. forces stationed abroad highlights our
15-32
Shipboard Medicine
nation's dependence upon forces afloat to project American policy throughout the world. All of
these factors point to the increasing importance of the amphibious forces in general and to the
LPH/LHA types in particular.
Figure 15-17. A starboard view of the general purpose amphibious assault ship USS TontUMi, LHA-1,
during 8ea trials (U.S. Navy photo^aph),
These ships, especially the latter, have a definite and readily apparent need for the Fli^t
Surgeon's unique operational and medical expertise. Ileet readiness would be well served by the
Flight Surgeon's permanent assignment to the LHA, on the same basis as his current assignment
to the CV.
15-33
o
CHAPTER 16
DISPOSITION OF PROBLEM CASES
• " " ' \'
Introduction
Section I: Medical Disposition
Introduction
Medical Disposition
Section H: Administrative Disposition
Introduction
Administrative Dischargeis
Classes of Problems
Section III: Aviation Disposition
Introduction
Identification of Problem Cases
Fitness for Duty
Local Board of Flight Surgeons ' "
Special Board of Flight Surgeons
The Board of Flight Su^eons at th^^rfeau of Medicine and Surgery
Conclusion
Appendix 16-A. Medical and Administrative Disposition Channels
Introduction
The etiology and resolution of people's problems is discussed in other sections of liiis
manual; the subject of ^is chapter is the disposition ^of people whose problewa are mch fltat
they may not be able to continue to serve effectively or safely. This discussion deals with
questions such as (1) what to do with a member of the military who has developed a medical
problem which might disquaUfy him from active duty, (2) how to help the command relieve
itself of the burden of a person who cannot or will not function with sufficient maturity and
responsibiUty to become an asset, and (3) how to charify the classification of someone assigned
to special duty when a question arises as to his continued qualification for sucHv$tt,%8iipii(ient>
Instiructions from a variety of sources offer guidance in these considerations; it is recommended
that a Flight Surgeon have, readily available, at least those listed ifl Table 16-1.
Other references should be in a fUe maintained hf^e AdttiinistratMe Officer in the hospital,
dispensary, or ship's medical department. Recommendations prepared for action by higher
authority will achieve an added measure of credibility if all provisions of the appUcable
16-1
U.S. Nffrat Flight Surgeon's IV^ual
Me 16-1
Instructions for Medical and Administrative Disposition
MANUAL OF THE MEDICAL DEPARTMENT
general instructions arrd
physical standards
BUMED INSTRUCTIONS:
1910.2G medical boards
6320.1 1C , transferto Veteran Administration
, faciliti*^
1910.3B unsuitability/personality disorders
5300.4 A alcoholism/aviation persannsl
SECNAV INSTRUCTIONS:
1900.9A homosexuality
5300.20 alcoholism
5355.1 A drug abuse
OPNAV INSTRUCTION: 6330.1 alcoholism
SUPERS MANUAL
ARTICLE NUMBER
(or)
MARINE CORPS SEPARATION
MANUAL, Ch. 6, Paragraph:
3410180 ........ .6001 .
3420181 6002 .
38501 20 ........ . 6003 .
3420184 . . 6016 .
' 34^f8S ........ .60iy .
3850220 . ; '. 6012 .
1860120(3850220) e012.1a
3420270 6021 .
3420175 6017 .
3420183 ........ .6016.1g
•■t*l6l00 . : (Chapters)
policy concerning misfits
definitions; reasons for and types
of discharge
determination of type of discharge
unsuitability
misconduct
obflWniarict of the government
■ • i
conscientious objection
flood of the seh^ba
drug abuse
drug abuse (exemptee)
officer performance
International Classification of Diseases, World Health Organization, current edition,
i WeaRPSJ'c an^ Statistioal Mapual, American ftychiatric Association, current edition.
16-2
Disposition of Problem Cases
instructions are addressed and if the instruction is then specifically cited. For example, a typical
concluding sentence to the report of a psychiaMc' eVtftiatiofl^eComniendmg tlie'M^^
separation of a member because of malperf ortfiattce attributed to a personality disorder might
be, "It is recommetided that (name) be administratively separated from the naval service by
reason of unsuitabihty in accordance with the provisions of BUPERS MANUAL Article
3420184."
As a final introcliietory comment, it should be noted that these instructions are changed
frpm time to time; several were revised during the preparation of thi§ chapter. It is incumbent
upoTi the Flight Surgeon and his administrative staff to insure that his own series of instructions,
is current. -,;
SECTION Is MEDICAL DISPOSI'EIpN
Introduction
In the event of a medical problem which might degrade n m^ialwf's iteess to continue
active service, the question of disposition must be addressed. This is typically done by
convening a Medical Board. Medical Boards afford an opportunity for formal discussion and
evaluation of a patient's case, review of his clinical, health, and other appropriate records, and
formulation of a carefully considered recommendation to higher authority as to the member's
fitness for continued service. Medical Boai-ds.iiQUld 1^ «©Wened mth» f^IoWBg; ease^: ..{in,,
1. Aphysicaldefectislikely to preclude 'furthWiAilitary service. "
2. Further military service is likely to aggravate an existing problem.
8. An inerdinate amount of hospitalization or close medical supervision is anticipated.
4. A member's condition is temporarily incompatible with unrestricted duty, but full
recovery is anticipated.
5. The ultimate restoration of function is uncertain, and there is a desire to follow the
patient for a short period.
6. A member's condition is such m,tQ require geographic or other limitations on
assignments.
7. There is a question of mental competency.
8. A patient refuses indicated treatment. .j t-
9. There is a need to formally document a condition which is lik«iy to recur (as in the case
of a man who developed depression or arthritis while on active duty, but, with
16-3
U.S. Naval FU^t Surgeon's Manual
treatment, the condition improved, and he was asymptomatic without treatment at the
time of retiremralt or rele^ ftoin active duty; 9 JJedijesl Board prepared at that time
could be used by him in the event of 8 later recurrence to document the
, service^comiected origin of his problem).
Medical Disposition
Composition of a Medical Board
A Medical Board normally is composed of two medical officers — the doctor who took care
of the patient and that doctor's immediate superior; a third member may be appointed when
apprdpriate. A dental officer should be a member of the Board whenever'^ patient's couditiott
relates to a dental problem. When the patient is a reservist, one member of the Boaid should be
also. When there is a question of mental competency, there must be three members of the
Board, and one must be a psychiatrist. A FUght Surgeon should be a member of all Boards on
naval aviators and naval flight officers who are returned to full duty or limited duty.
Convening Autfacwtty for Medical Boards
Itifiie^ Bomdk mdy^bB convened by the commanding officers of all Naval Hospitals, all
Naval Stations and Naval Air Stations in CONUS, all major Marine Corps activities in CONUSj
all Naval Training Centers, and the Naval Undersea Medical Institute. The Convening
Authority prepares an endorsement for each Medical Board before forwarding it to a higher
authority and, in many cases, is authorized to act on the recommendation of the Medical Board
without Waiting -for Bureau review, thus avoiding costly delay. Thereisno longer a requirement
that patients be admitted to tiie hospital for a Medical Board. Qutpapf Medicd Boards are
often more convenient and more expeditious and require otdy iJiat the patient be as^ted to
the command of the Convening Authority on the day the Board is held (easily accomplished by
no-cost TAD orders). The opinions and recommendations of specialty consultations can be
incorporated as enclosures to such Boards.
Medical Board Report
The report of the Medical Board, to be submitted via the Convening Authority, should
present, in narrative form, all pertinent data concerning each complaint, symptom, disease,
injury, or disability presented by the member which causes or is alleged to cause impairment of
function. The narrative must be clear, concise, and sufficiently comprehensive to enable a
reviewer who cannot see the patient himself to render an appropriate decision regarding the
recommended disposition. Above all, the member^s current physical itatus must be dearly
reflected^ The report consists of three main parts — an introduction, a niarratiVe account, and
recommendations. ' i
16-4
Dispoaitioii of Problem Ckses
The introductory section should contain such information as the patient's age, marital
status, rate or rank, years of service, nature and duration of symptoms which precipitated the
evaluation, and the :qnitial diagnosis. ,
The narrative section should be no more, and certainly no less, than the narrative summary
prepared after aU hospitalizations and periods of outpatient treatment. A review of the problem,
a pertinent background history, and appropriate physical, mental, and laboratory examination
data are essential. The narrativ@ should include all positive and aUpettinfent mpM'm fin€^^^at
the time of the initial evaluation^ -the treatment and procedtires instituted, aiid the pati^- S
general progress under this regimerti ■ ' i .
AU Medical Board reports should conclude with a section presenting the member's current
physical status, the anticipated future course of his condition, and the Board's opinion as to the
disposition most appropriate in hls ease* Thete p® only fourreeommeniatioiis j^di aMe^i^
Board may make:
1. Fit for FuU Duty. The member is conside#&d.ftii%'qtialified for all duties appropriate'td
his rate or rank;^ without physical or geographic restrictions. It should be clear that it is
only with a recommendation for return to fuU duty that a determination of an
individual's flight status can be made. A person not fit for full duty is not qualified for
special duty, such as aviation. *Purlhermore, aviation personnel cannot be returned to
any flight status by Medical Board action; this requires a separate determination which
will be discussed in the section on aviation disposition.
2. Fit for Limited Duty. The member is considered fit for duty, but this must be restrieted
CQitimensuFat& with his condition. A limited duty status is arbitrarily restricted in time
to six months and geographically to CONUS; additional qualifications can be
recommended, as appropriate (e.g., after laminectomy, a man might be restricted from
lifting or long periods of standing; a man recovering from a depressive episode might be
retained m an area where outpatient psychotherapy is available, etc.). Wilhin six months
following a Medical Board recommending limited duty, another Board must be
convened which can make any of these four recommendations, including another period
of hmited duty. Normally, a maximum of tiiree such six-month periods wfll be
approved. If a person is not fit for fttll'iutf' by that tithe, it is usually most approprttftt?
to refer his case to the Phy8icd i^W4tiqn<Bofflfd. i ' ' i) < ^ t " •
. . . I . ■
3. Aclmitt^trative Processing. The patient's case is most appropriately handled thfough
'■ administrative, rather than medical, channels. Occasions for this recommendation arise,
for example, when a person must be hospitalized for treatment of a disqualifying
condition which he fraudulentiy denied having had at the time of his enlistment, or
when a person who cannot adapt to mihtary S^Mce befeause of a personality disordfii'ife
Ids
U.S. Naval Fli^t Surgeon's Manual
hospitalized because of a raanipuktive suicide gesture. Attention is in,vited to the later
section on administrative disposition.
4. Referral to the Physical Evaluation Board. The member is physically or mentally unfit
for continued military service and should be medically retired. This recommendation
■ I ' ■
Whenever a Medical Board is contemplated, a Disability Evaluation System Counselor
(DESC) is appointed to insure that the patjent aniasstaiids his rights. The patient will, unless
0X0m is M^ tl^iie ii>@iDiiito«iailiii0n hM-physical or mental healthy be tevil^d
to meet with the members of his Board to discuss their findings and recommendationsi If he is
satisfied with these, he must sign a statement to that effect; if he wishes to rebut any of these,
he is given five working days to prepare a formal exposition of his objections. In the latter case,
Board members have the option of preparing a surrebuttal statement. After endorsement by the
feiivening Authority, the report is sent for a higher review. >
Nieeissity > f^ AcflWiltfe Medical Board Beporting
Mfonftatferi'^^iAed Ift- tfedteai l%f)<*rts nitty plif an importaat role in determining
a person's eUgibUity for a variety of benefits, as well as in Hie immediate disposition of his case.
It is important, therefore, to include in the report all available information, with adequate
documentation, concerning the origin, nature, conduct status, and aggravation by service of any
condition discussed. Wherever possible, impairment of function should be reported in terms of
objective tests or findings rather than as opinion or conjeciUire. Where no impairment exists, this
should be «laldL Wjete-ian Mpafement involves an upper extremity, the term "handedness"
should be specified. Sufficient Ulformation for proper assessment of overall '^lliility or
functional impairment must be presented. In cases referred to the Physical Evaluation Board,
the report must contain information on all rateable conditions, even if some do not represent
functional impairment or lead to unfitness in and of themselves.
111.' , , , . .
Medical Disability
When a Mftdieai^^id reppmmendf that %^iint;be considered unfit f«r ®(^ntiflued
his case is referred tStnip^Cfea^WlBi^iitlfl fefilaMofi iiJif d (OPEB). ^he CPEB consists of one
medical officer and two line officers. When the patient is from a minority group or is a reservist,
at least one of the members of the CPEB will be from that group, insofar as is practical. The
CPEB, solely on the basis of the Medical Board Report, wiU render an opinion as to the patient's
fitness for duty. If the Board members determine that he is not fit for continued service, they
will rate his disability with a percentage figure which they believe to accurately reflect the
extent of impairmeKf ll^d PWitiWe ip^ the civilian job mai;ket.,J^|I^Iishing
16-6
- Ilisposition of l^Uem Gases
diEiability Jafings is the prerogative of the CPEB and not the Medical Board-whieh referred the
caise. The role of the Medical Board is to describe and document the impairment with sufficient
clarity and accuracy to enable an appropriate CPEB determination. It is especially important
that conjecture in this regard by members of the Medical Board to the patient and/or his family
be avoided. • !•> ^ - i .oil-Mii 'pm.
CPMB's 'ife(SorBfemdat»n^is wturned^tQ i0aM^Wmii'lt hei^^kjmBe§itQAm%9piiMif^
paperwork is passed to the Physical Review Council and the Judge Advocate General's office for
review before approval by the Secretary of the Navy. Should the patient be dissatisfied with the
CPEB's recommendation, he has the right to appeal to a Formal Physical Evaluation Board
(FPEB). There are three FPEB's, and the patient may choose to atppear in person before one of
these or to request that one of them fevim*r^^Jite#rt*i4l»Gq^m (alull asd
faiii, or a prtfnftg^a», hearing, respectively)<ip^^ di|i^^©ag#i bt.lias^f.^ from other
military medieal consultants and be represented by military attorneys at no cost to himself, or
he may retain civilian consultants and civilian attorneys at his own expense. The recommenda-
tion of the FPEB is passed to the Physical Review Council whose recommendation is then
r^tamed fo 'tfie patiehb xTf- he Eematoiiidissatisitd, he may again appeal, either with a full and
fair or prima fade hearing, before/ the Fhyacal Disabflity Review Board* Their recommendati«^
W tenm^'tiSff fflife;:<|ad^ Advocate General's office and then passed to the office of the
Secretary of the Navy for a decision, for which there is no formal appe^ wjeehi^Jism. Every
effort is made to insure the patient fair and impartial treatment. ; ,
If it is determined that the patient wfrnot fit fo* :®ontini!^>ikrvice aHi/Htatfefe; disability
rating is less than 30 percent, he i& separated iwith a lump sum severance paf^ment,'l|if.iai^«^B^
of wfefeh is dietermined % MssliEiMgevity, his tale opaaiifc, and the actual piir®eiat^ft*iitol)iEt^
established. This terminates his relationship with the military, and he is accorded no other
monetary benefits (unless he has aheady served on active duty for a sufficient period to have
earned a retirement pension). • ' . ,
If it is detbrmined that the paiefttis unfit for active d«ty, and hk dW>iH<5f^ fating: at lisa«S
30 percent, he normaUy % piaeed oti the Temporary Disabihty Retired List (TDRL) for a period
not to exceed five years. While on the TDRL, his case is reviewed every 18 months at a military
medical facility. The report of this review is essentially another Medical Board, and it should
clearly document the difficulties and successes he has experienced in adapting to civilian life.
His disability rating may or may not change as a result of ^esse TDRL evaluations. At any time
while on the TIjIRL, it may be determined that a patient's condition has improved to the point
that he is tOT.?e again fit for duty. He then is invited to return to active duty, and his years on
the TDRL are credited toward his longevity, but not toward promotion or retirement eligibility.
l6-f
U.S. NovaliEli^ iStngeonr^ Mantial
^liM M.«teOfeNft6titEfetjieto »eiw4!!i|ts;h4l^^fe!bi^^ and all other benefits
cease. After five years on the TDRL, most patients are moved to the Permanent Disability
Retired List (PDRL). There is no necessity, however, for maintaining a patient on the TDRL for
the full five-year period. He can be transferred to the PDRL at any. time it becomes clear that
there is no reasonable likelihood of his Iteing restored to ail active duty itatus.
Iffiefewsan the THRLiorlthiBiMJRIiv'a p©i*on receives medical disability compenjiiljoli
payments. These are determined by multiplying the current fmonthly base pay for the rate or
rank he had achieved when medically retired by the percentage of disability established, with
the latter limited to 75 percent — the maximum a person could receive in retirement pay after
30 years service (e.g., an 0-5 with 16 years active duty who incurred a disability rated at
|0!|>ll^llt W(Mi receive 50 percent of the l3a^'T^y?*ter «b'©4 wMif M' fesm mmce. Had his
disabifitf heeffl tatiSd' at ltPf>ercent^ |Be»#Ofl^'Tei^ive 75 percent of the same base pay.). Any
person on the TDRL or PDRL becoihes a Veterans Administration (VA) beneficiary. In the
situation where disability payments, computed as described, would be less than those derived
from a VA table, which considers only percentage disability and not rank or years of service, the
patient is fttlSted' fe' waive his payments ftterf :^tflry tol #iteftBf|t^eife the higher
paymetffeitfam thfe*'VA*iniii wewldi btfifiie case with many enlifitej3«|ME®ple<atiiil ftstoe ju^
^Gl«8 S«iifit*feW years of active duty. In either case, medically retired people retain essentially
the same rights to the use of base facilities (commissaries, exchanges, etc.) and to miUtary and
CHAMPUS-sponsored medical care as enjoyed by people who retire on longevity.
^#alst 1«lit@h will help one to understand the importance of disability payments for many
p@@plf 'a|i^€^ch^ fttluntory retirement on longevity is that all disability compensation for
l}i#g^i#tth aetive dtlt^ prior to 25 September 1975 is exempted from Federal income tax. For
Aose whose active service commenced after that date, disability must have been incurred in
combat-related circumstances in order to qualify for the income tax exemption. As an example,
if a man reports a physical disability at the time of his examination for retirement after 30 years
service and is awarded a 50 percent disability for this, he would receive 75 percent of his base
pay beeaiiiie iJf hiSi years on active duty, and two-thirds of this amount (SO pwcent of his base
pay) wMld' he ''^lEeMpted froitt FediKpal taxation. Because of alleged abuse of this system, PEB
aetitiE' tlie case of senior line officers and all medical officers isr^eviewed by^a Congressional
General Comments
In Appendix 16-A, the items which have just been discussed are summarized ahove the sohd
korizontal iiine. This e*an be broadly refeiffed to a^ the dlipoatibn of aetiVe dupty p'^Soiind w
develop an illness or sustain an injury which renders tiiem unedile to continue to ftinctibii
IMspositioii of Problem Clases
effectively. They are assured that if fjienr ability to provide for themselves in civilian life should
become compromised, they will be compensated. On the other hand, the military assumes no
responsibility for inherent defects in character development which may cause an individual to
be unable to function effectively, with the maturity inherently required, in a military
orgaimation< Those who,, cannot accept^ the xe^aiisihllity of mihtary service are dealt wi^
administratively, rather than medica^f « md their dd^i^^pite are not compenBated> Qi^oafj^^
of people with sucKiioninedical problems is suiamapzed below the solid line in App^dix 16-A.
The question of good and bad, and right and wrong, might arise at this point. It should be
clearly understood that whether or not an individual's situation constitutes a problem for him
or society ia ane issue. Whether this con<j||tion might compromise his effectiveness in military
service is a sc^aritte issue. Tf gpeoific, people, with certam pe^fi|jti{^;^;EU$or4Qp^|P0g4®^^p
choose to derive pleaaire from a certain drug at sa®h<jtimes and uialif^aieh cBeM m not
to interfere with tlieir job performance, people whose sexual preferefice is — while not
orthodox — not disruptive to society when conducted by mutual consent in privacy, and people
who genuinely develop an irreconcilable conviction that war is wrong, might all make positive
contributions to society in many ways. Under conditions as they now prevail, however, they
cannot function effectively in military service. For that reason, an avenue lo provide for their
^iildiittige hy administrative means Wto esfi^lMlfed.'''^i3 refer to their gituaitiQns in terms of a
"defect" is not to connote a value judgment, h»t is merely to differentiate their reasons for
being unable to serve effectively from those compensable reasons which are related to disease
and illness.
16-9
U.3, N«v4.Wt %m^^ki^^
Introduction
Most of the problems to be addressed in this section, with the exception of alcoholism,
homosexuality, and conscientious objection to military service, apply primarily to enlisted
personnel. This should ttOf'3b#ied«ififbfed*^'a iEtdtie judgment as to ffi^ffelalKre worth of erilisfcftd
tersus offttei^6*ii«ft^i It & eirftpiy reffleetivie of the iselectieit -iftteria impdifed OTft officer
candidates. Almost all officer procurement programs require either an extended period of
satisfactory enlisted service or the attainment of a coUege degree, either of which tends to
eliminate people who would have the kinds of difficulties to be discussed. Many of the
instructions which wiU be outlined apply specifically to enhsted personnel. BUPERS Manual
Article 34101 Oi9 addresses #6' ^^tn^|tl?ative dispositiiJn>'df ijffiteter per Sditei Mth firlSBlems
comparable to those ^^^iffiii#M f^ir%ifflrtl'petefllnnel Below. " ' <*'
The discussion of problems is organized around the specific instructions invioHed;
Corresponding MAECQRSEPMAN par^igraphs are indicated iri |iarentlieses.
.i.w.>.;B»rt;> . w ' •
BUPERS lyiANUAL ARTICLE 3420180 (6001) - Administrative Discharges
This instruction provides guidance as to the position of the Navy in regard to those who
carnaot adapt to military service;
, . .it is not the intention of the Chief of Naval Personnel that the
Navy be burdened with misfits who have neither the ability nor the
desire to become good sailors. On the other hand, it is essential that
there be dedicated and purposeful effort devoted to the development
of those marginal memhers who give indication of developing into
useful members, albeit not so rapidly as their contemporaries. At a
time in the development effort, it may become impressively evident
that the marginal member is not going to adjust, at which point
further retention will become a burden on the command and a drain
OB resources.
There is an injunction to commands to process cases for administrative separation in strict
comphance with the poUcies and procedures set forth in the relevant instructions in order to
avoid delays in final action, and to dfapose of all pending miUtary offenses under the Uniform
Code of Military Justice (UCMJ) prior to administrative processing.
16-10
DiBpositioii of ^blem Ckises
SUPERS MANUAL ARTICLE 3420181 (^2) - Policy and Defmitions i
of Enlisted Personnel
This article defines such terms as "discharge," "release from active duty," and "administra-
tive separation." The 12 formal reasons for discharge are listed below:
1. Convenience of the Government '
2. Dependency or Hardship ' • . n .
3. Disability
4. Expiration of Elilistment ^
5. FulfiUment of Service Obligation .
6. Minority . (T
7. Misconduct
8. Security i H
9. Settt»ttce5|f aGotirt-MsB*tial '
10. UnsuitabiUty
11. Personal Abuse of Drugs ,
12. Good of the Service
Confusion often arises between these reasons for discharge and die type of dischai^ graijft^.
There sae only five types of discharge; they are listed with the character of separation which
corresponds to each:
1. Honorable Discharge hnnori^t. ■/ ' AN .?•<■ n«
2. General Dischfli^ u,nder honorable conditions
3. Discharge Under Other Than
Honorable Conditions ............
4. Bad Conduct Discharge
5. Dishonorable Discharge . dishonorable
A Dishonorable Discharge can result only from the approved sentence of a General
Court-Martial; a Bad Conduct Dischai^e can result from the approved sentence of either a
Special or a General Court-Martial. Coiifts-martial can mcpnunend niore f ayorablcr discharges,
but these commonly arise from administrative, not judicial, action.
under conditions other than
honorable
BUPERS MANUAL ARTICLE 3850120 (6003) - Determination of Type of Discharge
for Enlisted Personnel
This Article establishes the criteria for each of the types of discharge. An Honorable
Discharge is conditioned upon (1) eligibility for discharge by any of the 12 reasons listed
above, except misconduct, sentence of a court-martial, and good of the service, and (2) "proper
16-11
iiamtm^ behavior with proficieiitMi^ industrious performance of duty "This is operati6iiaI^
defined as achieving a final average of not less than 2.7 in all quarterly marks aUd an average of
npt less than 3.0 in military behavior grades during the current enlistment, j >
AGeni^'al Dischai^e is issued by reason of misconduct, as well as by the reasons which apply
to HotiOHible Dischaj^es where the quarterly marks are inadequate to justify fin,.j|Ionorable
Discharge.
A Discharge under other than Honorable Conditions may be issued by reason of
misconduct, security, good of the service, and sentence of a court-martial; Bad Conduct and
Dishonorable Discharges result only from judicial action and are not of concern here.
I^e tern ^'unfitness" appears in the most recent copy of this instruction. It is ?recE>nitttended
that this word be striken. "Unfitness" was a reason for administrative separation which was
more serious than "unsuitabUity," but it represents less grave offenses than would be processed
under the "Misconduct" instruction. In 1976, causes for proceeding under the old "Unfitness"
instruction were reclassified underrevisedinstruetioris for "Unsuitabihty" and "MisconAict,":and
tite "Unfitness" instruction was deleted. "Unfitness" should not be eonfused with "unfit," a
te«9 used to connote a member's not being physically qualified for active duly.
Qasses of Problems
BUPERS MANUAL ARTIOEl S420184 (6016) - Unsuilability
This ■& likely to h6 the Article most often referenced. In general terms, it prcfvides the means
for ijie |i^55|ijpsj^iitive sppstrsrtion of enlisted personnel who have sihown no reasonable likelihood
of becoinittg assets to the service, and/or who have become burdens on their command, but who
have not become involved in major administrative or legal difficulties. The type of discharge
arising under this instruction wUl be either Honorable or General, whichever is indicated by the
performance marks. The causes for separation by reason of unsuitabdity are
1. alcohol abuse, when a person refuses to participate in, or has not benefited from,
alcohiOl i-ehabilitation programs
2. financial irresponsibility
3. personality disorders, when they are associated with malperformance and when they are
diagnosed by a mediieal officer or a psycholo^st
4. homosexual or other aberrant sexual tendencies with no acts involved
5. inaptitude
16-12
Disposition of Problem Gases
6. apathy, defective attitudes, and inability to expend effort constructively
7. unsanitaiy habiti, including repeated venereal infections.
The problem with which a Flight Surgeon might most often be involved is refewed to in Point 3
above - personality disorders. Diagnosis of a personality disorder by a medical officer (not
necessarily a psychiatrist) or a psychologist is a prerequisite to processing here, but not for any
of the other causes hsted above. One of the major goals of the psychiatry course at NAMI is to
oJBfer student Fli^t Surgeons a thorough review of the field, on the basis of which they should
be j^tt^r prepared to write a comprdiens^e, aecurat%;fa4^@d^^ A
review of this procedure can be found in Qlmpm^i^ Psyi^wtry.M^^ well
over half of the Navy billets for p8ychia?^|i|^ were unfilled. Thus, Flight Surg«pi||ani^|
realistically expect ^o imi it j^f;xGasip^y,^eG to.peif|pn^.evj|I^a.tion9 qf .iJfeU t^^.
Diagnosis of a personality disorder, in and of itself, is not a sufficient cause for discharge,
discharge can only b«l recommended , . if the nature or severity of tiie personality disor4er
pxealudes the member's adequate a<^u£inient to service life or is coupled with 8ubstandai#
performance to the extent of the member becoming a command burden." In other words, the
personality disorder must be associated with malperformance. This may be manifested by
inefficiency, obstructionism, inability to fit into an authority structure, administrative
difficulties, lack of reliability, or in many other ways which might make the person more of a
burden than an asset to his command. Before processing, the member should have been
counseled in regard to his deficiencies and shoiidd have been given a reasonable time tOk^adjust. , ;
This Article directs that commands wiU make available to the medical officer or
psychologist performing the evaluation all pertinent information and records. It also
recommends that commands "... maintain liaison with the medical authority to ascertain if any
particular action of the command n^at smst flie member in adjusting emotionally to the naval
service." In the latter regard, restraint is reeonunended. It often is tempting for tbe Fli gh t
Surgeon to feel that he can "help" someone in bis command by using his professional influence
to manipulate his environment. In most cases, such well-intended intervention only postpones
the eventual disposition at the cost of added unhappiness for the person involved and
frustralion for ti^ command. Finally, a recommendation regarding disposition under the
provisions of this Article is only that — a recomjjiendation to the command. The person
involved should not read the report, nor ^ould the recommendation be discussed with him,
until the command indicates its intended action.
By a 1977 revision, the prerogative for commanding officers to separate many people falling
under the provisions of Hie ArttM^ locally, without awaiting Bureau action, was rescinded. At
this time, all such recommendations must be approved by hi^er authority before disposition is
16-13
U.S. r^aL Fli^t SurgicQn'B IVUnual
effected. An exception to this is that commanding officers of naval hospitals retain authority to
discharge people with certain types of personality disorders under the provisions of BUMED
Instruction 1910.2G.
aitWe it gifd^iHing dott^eni iaa^ military psychiatrists ftat "branding" people with a
peitsott^dity disorder "label" should be avoided. Senior staff psychiatrists in at least one ma^or
psychiatric training center have refused to do so for some time — recommending in almost every
case referred that the disposition be based on the member's demonstrated performance. In part,
this may have arisen from consideration of the present and projected psychiatric staffing. There
is also a geniiin^ regard, however, for the; cQiE8iB^eht5ei"tbf the individual of assigning him a
dii^osil' l^eh is iSefi to ratjonalisse dJt e^:^se his behavior and which, tiberfefore, might restrict
growth toward maturity in the future. Regardless, now that authorization for prompt Ibcal
separation of members with personaUty disorders has been withdrawn, there will be few cases in
which any advantage will be gained by such a diagnosis. If a member does not manifest either
"inaptitude . . . apathy, defective attitudes, inability to expend effort constructively" or one of
the other reasons for processing under this Article (aU of which are now handled similarly and
M of wMch am fefe d6ei*aienteA by his performance), it is most unlikely "that he or she has a
pi^onalilf disorder in tlie first place;
In order to protect career-motivated people against the possibility of an ill-considered
and/or impulsive recommendation of a command that they be separated under the provisions of
the Article, any enlisted person with over eight years of active duty has the ri^t to be
represented by military counsel. The raembier ipay make statements in his or her behalf and
have his or her case considered by an Administrative Discharge Board appointed by the Bureau.
Officers are accorded this right after three years of active duty for the same reason. It is
assumed that the majority of problems which fall under the purview of this Article should have
become apparent belFoTe the conipl^lion of fiiese respective periods of service.
B^B%iM^i^i;AiL MTICLE 342OI85 (6OI7) - Misconduct
Hie people to be processed under this Article differ from those discussed above, onty in that
thi^ h*ye involved themselves in serious administrative and/or legal difficulties. Ordinarily, a
Discharge under other than Honorable Conditions will result unless either a General or
Honorable Discharge is felt to be justified by the particular circumstances of the specific case.
Discharges by reason of misconduct can only be effected by Bureau action. The reasons for
reoommending discharge under this Article are
1. frequent discreditable involvement with civil and/or military authorities (e.g., an
est^jpshed pattern of shirking, f aHiij§^o piiy debts, failing to support dependents, etc.)
1614
Dispositioji of PtoWem Cases
2. homosexual acts and other manifestaliolis of mmsi pm$tmn (proeessmg here is
mandatory)
3. rlrug abuse, except as excluded under the drug exemption prc^ani, and sale and/or
trafficking in drugs (for the latter, processing is mandatory)
4. conviction by civil authorities (or action taken which is tantamount to a finding of
guilty) of an offense that authorizes the death penalty or confinement for one year or
more ttnder the tJCMJ. The offense may be consMered a felony, involve drug Abuse or
sexual perversion, fraud, deceit, larceny, wrongful appropriation, or the making of a
fake statement.
5. pEoeurement of a fraudulent enhstment (excepting a minor who misrepresented his
age - see BuPers Manual Article 3850260: Disffliarge of Enhsted Persoimel by Reason
of Minority)
6. continuous unauthorized absence for a period of at least one year.
This Aititte 4<jes not specifically require a psychiatric evaluation; however, one may be
appropriate in some cases. The instructions which relate more directly to homosexuality
(SecNav Instruction 1900.9A) and drug abuse (BuPers Manual Article 3420175) do require a
psychiatric and medical evaluation, respectively. All enlisted members processed for discharge
by reason of misconduct are accorded the same rights provided those with more than eight years
active duty who are processed uuder the uniMitdjility instritoti<>n.
BUPERS MANUAL ARTICLE 3850220 (6012) - Convenience of the Government
This Article provides for the administrative separation of enlisted members prior to the
expiration of their obligated seirice for any of a variety of reasons; among them are
1. general demobilization or reduction in strength of a specified class of personnel
2. erroneous enlistment (differentiate from fraudulent enlistment - misconduct)
3. conscientious objection (see also BuPers Manual Article 1860120)
4. obesity,(see also BuPers Manual Article 3420440)
5. to provide early separation for sueh reasons as may be authorized (e.g., At certain
times, separation up to 90 days before the expiration of certain members' obhgations
has been approved in order to permit them to be present at the convening date of a
civilian education program — a "school cut.")
6. when a member has a condition which interfers with his performance of duty, but
which is not considered a physical disability (e.g., somnatnbufiaa, enureffls, allergy to
all available umf orin fabrics, motion sickness, etc.)
16-15
U.S. Naval Snrgeon's Manuid
7. inability to be assigned appropriate duties because of security considerations, even
though the problem may not be so serious as to justify disposition under the provisions
of SecNav Instruction 5521.6 series, which deals specifically with the security program
8. dependence or hardship, even though the condition may not be so serious as to meet
file criteria specified in BuPers Manual Article 3850240
9. repeated unsatisfactory grades or unfavorable comments on performance evaluation, or
consistently substandard personal behavior, even thou^ this would not warrant
disposition under other directives
10. at the written request of a member on the basis of her pregnancy (see also BuPers
Manual Article 3810170)
11. when a medical officer determines that a member in any officer candidate, training, or
profiurement progHon is not physically quaUfied for appointment as an officer
12. marginal or substandard performance during first enlistment
IB. Additionally, there are numerous administrative probletos which are dealt with by this
instruction; it is unlikely that the Flight Surgeon will be involved in these.
There is normally no authority for local separation under this Article. The type of discharge
awarded is usually determined by the quarterly marks, as with unsuitabiUty separations.
BUPERS MANUAL ARTICLE 3420270 (6021) - Good of the Service
In ord^ to avoid the time, expense, and pos^le emb^assm^t involved in a court<-martial,
an. enlisted member may request a Discharge under other than Honorable Conditions in lieu of
a^on under tSm UGAjJ if puniAment for his alleged misconduct could result in a punitive
discharge. K &m k approved by the Bureau, he will be discharged by reaion of the Good of the
Service.
BUPERS MANUAL ARTICLE 3421075 (6017) - Disposition of
Enlisted Personnel Identi&d as Dnig^^nwerB
When an enlisted member is identi&d as having been involved in the uie, posEfesdon, sale, im-
ti'^fer of marijuana, narcotic substances, lind/or'^^r controlled substances, the command
^aSi Urat refer hira to a medical officer, who ahal
1. determine, by examination, the physical condition of the member. If he is felt to be
physically dependent and in need of detoxification, he should be transferred first to an
appropriate medical facUity.
2. make the following entry (SF 600) in the Health Record if exemption is granted:
"(date) Granted exemption in accordance with SECNAVINST 5355.1 series."
16-16
Disposition of Problem C^es
3. determine what, if any, rehabilitation is indicated, and make an appropriate
recommendation to the command. Among the options are
a. counsehng by himself, the command, or whatever resources might be available
.locally
h. rehabilitation in a formal program, either inpatient or outpatient, at a Counseling
and Assiatanfce Cfentef (GAAC)
c. rehabilitation at the Naval Drug Rehabilitation Center (NDRC), NAS Miramar, CA
4. in the event of consideration of teansfer to NDRC, recommend assignment of either
Priority One (must he transferred immediat^]^ - arfter detoxification - for the safety
of the member) or Priority Two (all others).
All pending disciplinary action must be disposed of under the UCMJ before transfer from the
local area.
The Drug Exemption Program was developed as a means of helping people to discontinue
drug abuse. Specifically, it provides a one-time-only exemption from prosecution under the
UCMJ for those memberB who voluntarily disclose information ab^ul their drug use in orfe to
receive needed rehabilitation. A member may not be issued a discharge other than Honorable
for drug abuse solely because he volunteered for treatment under the Exemption Program. In
order to quahfy for exemption, a member must voluntarily disclose his drug abuse, or must
apply within 24 hours after being informed that he has been implicated in another member's
exemption disclosure, or must request exemption after one or more screening urinalyses have
been reported positive. Those formally chafed or oftieiaUy warned by eivil or military
aulhorities in regard to an offense they had not previously disclosed^ those involved in the sale
or transfer of drugs, those guilty of any dffljg^rftlated or drug-induced offenses, and thosfe
previously identified as drug abusers are not qualified for exemption. BuPers Manual
Article 3420183 and MARCORSEPMAN paragraph 6016. Ig provide that members may be
separated by reason of personal abuse of drugs (other than alcohol) with an Honorable
Dischjurge when they either volunteer for exemption or are discovered in a routine urinalysis
screening program, provided that
1. theit (ecorli indicates laek of potential for continued semee
2. thdr need for long-term tehdbiUtation results in traftrfer to a Veterans Administration or
dwfian facility, or they reftise or are unable to participate in, cooperate in, or complete
a drug abum treatment and rehabilitation program.
Such discharges are normally not affected ". . . until all attempts have been exhausted to
complete a minimum 30 days counseling or rehabilitative assistance."
16-17
U.S. Novalf light Surgeon's Manual
It must be emphasized to people granted exemption that this is accorded once only. If, after
the exemption has been conferred, they choose to again involve themselves in any form of drug
abuse, they wiU be dealt with administratively in the same manner as persons who did not
qualify for exemption. They will be processed for separation by reason of misconduct.
SECNAV Instruction 5355. lA, with enclosures, sets forth the basic policy regarding drug
abuse, defines relevant terms, and discusses the Exemption Program, Urinalysis Program,
rehabihtation policy, and security clearance pohcy.
SI^NA? INSTRUCTION 1900.9A of 31 July 1972 - HomosexuaUty
Tim loBtmction prescribes the authority, criteria, and poUcy for the separation of members
of any component of the naval service by reason of homoseiiiaBty. The term "homosexaali^,"
as used here, includes the expressed desire or tendency toward such acts, whether or not they
were actually committed. The military considers such persons security and reliability risks who
bring discredit to themselves and the service. They are regarded as . . liabilities who cannot be
tolerated in a mihtary organization." Knowing participation in a homosexual act or strong
tmdencies towsnrd hoinose^ilid b^&vioi require processing under this Instruction which is not
limited in its scope to "confirmed" or "way-of-life" homosexuals. Intoxicktfoiai ^0^ Aot
CQUsitute m emmmimUoMoemvtilmUiixc^ but it Is a circumstsutce which may be conisfdered
in determ Mng tile 'final dispositioa ol m mdinduial eaae.
When homosexual behavior or tendencies are alleged, commands are directed to investigate
the matter thoroughly. If the information is determined to be unfounded in fact, the matter
inay be dismiascid loc#y. Otherwi^, the member's case must be referred for administrative
prot^sing or trial by cottrt-martial, m approprfate for the categories hsted: ' '
Gins* I: Homo&exuid conduct in which one party involved did not willmgly cooperate and
freely consent, or any homosexual act with a child under the age of sixteen. Disposition by
court-martial is most appropriate, although separation by reason of misconduct is not
precluded.
Class II: Homosexual conduct, while on active duty, in which both parties willingly
consented, or attempting a homosexual act by force, fraud, or intimidation. Processing for
separation by reason of misconduct is usual, fdthough court^mittlial may be appropriate in
some cases.
Class III: Persons who have homosexual tendencies or who solicit a homosexual act in the
^Afiieiice of aggravated circumstances. Processing for separation by reason of unsiiitability is
normally appropriate.
1648
Dispoffltion of Problem Gases
Class IV: Persons who have engaged in homosexual activity prior to the current period of
active duty and who denied this at the time of their enlistment. Such persons are normally
processed for administrative separation by reason of misconduct (fraudulent entry).
The role of the medical officer in such cases is sometimes misunderstood. He is not an
investigator charged with the responsibility of determining what did or did not happen. The
Naval Investigative Services Office will assign one or more agents to aid the command m that
regard. The primary function of the medical officer is . . to determine whether psychiatric
eiraltialioti is warranted as pitft of Ihe evaluation proces^ng tor appropriate disposition of
cases." If such an examination is recommended, it is to be conducted before the administrative
or judicial proceedings. If the person is found to be suffering from a neurotic or psychotic
disorder which detracts materially from his responsibility for homosexual involvement, or if his
homosexual behavior is a manifestation of such a disorder, he should be considered unfit and
should be afforded treatment and processed for separation on fliat basis. In the event that
psychiaMc eviiMaition rcwais information "which suppoili or confirms the charges against the
member, this will be useful to the command as the disposition proceeds. As in any situation
where a member might reveal evidence which could be used against him, the medical officer
should commence his interview with an appropriate review of the rights provided the member
under Article 31, UCMJ.
It is noteworthy that this instruction was "puBBshed in 1972 with the following
admoitttioJl: **Note^. . before citing this as a reference, ensure that a later Instruction has not
been promulgated." This would surest some anticipation that the official policy might be
modified. However, this has not been the case to date. Regardless of the personal convictions of
the command or the medical officer involved, the Instruction is unambiguous: "Processing ... is
mandatory."
SECNAV INSTRUCTION 5300.20 of 18 May 1972 - Alcdh«dttifa smi AledhiA Ahuie
Alcoholism and its associated problems are the subjeet of Clh^ter 1% Alcdkol Ahtise, Only
tiiei administrative disposition of alcohol-dep^dent people iviU be tlteeussed here.
Historically, alcohohsm was regarded as misconduct; the consequences of this were tragic, as
everyone involved attempted to conceal the problem. Medical officers diagnosed conditions
cleariy caused by alcohol alinse in terms which effectively disguised flieir origin. Line officers
and doctors tended to ^ore or rationalize blatant manifestatiotts of far'ad"«anced addiction,
and subordinates, peers, and superiors alike oftSn eonspired po avoid prosecution of the
alcohohc - hoping, perhaps, that he would move on to another command before this would
become necessary. Typically, these well-intended gestures were detrimental. The alcohoUcs
16-19
U.S. Naval Slight Sui^ii% Manual
themselves experienced increasing guilt about their behavior and anxiety about the possibOity of
detection (some probably drinking more for this reason), and many were allowed to continue
such behavior until irreparable physical damage ensued, and/or some catastrophic event (e.g., an
aircraft accident) provoked official awareness and an unfavorable discharge, on the basis of
which they were denied treatment and eompensation for even far-advanced, alcohol-related
disabilities.
Rehabilitation efforts, based largely on the Alcoholics Anonymous model, were shown to be
enormously effective. Alcoholism in the military services was reviewed in the late 1960's, and
^^NAV Instruction 5t00.20 resulted. Alcoholism is now officially regarded as a preventable
aaid treatable disease which ". . , requnes the apphcation of enhghtened attitudes and
techniques by commwd, mpervisory, and healti* service personnel." The connotation of
misconduct has been ehminated, and disabilities related to alcohol are now eOTOpmsable. The
responsibility for prevention and the primary responsibility for obtaining treatment rests with
the individual involved, but the Navy will attempt to identify and treat alcoholics whether they
qpeifdy @ee|^ such mtervention oi not. Indeed, success of rehabilitation appears to be unaffected
by whe&er the individual volunteers for treatment or is ordered to a riiabiHtation program
against his will.
Rehabilitation facihties we oycgs^^l^ atseyerallpvels:
. J. ARD's - Alcohol Rehabilitation Drydocks, which are hne activities located aboard most
stations and many large ships around the world. While the technique and staff available
may be somewhat less sophisticated than those found at other facilities, ARD's have the
&tinet adyant^fe of not removing the patient feom the work and family stresses which
he may have used to rationalize his drirddng or from the supportive milieu which might
aid his recovery .
2. ARlI's - Alcohol Rehabilitation Urots, which are smtU wards operated as tenant Ime
activities in most naval hospitals.
3. ARC'S - several large Alcohol Rehabilitation Centers, the Alcohol RehabiHtation
Service at NRMC Long Beach, and the Alcohol Rehabilitation Program at NRMC
Portsmouth. The latter two add to the rehabilitation effort an effective educational
program directed toward enhghtening the non-aleohoHe phyacaan, irui^, psychologist,
and others involved in health care delivery, bringing them to a more realistic and
comprehensive awareness of the problem. While these facilities may have available more
advanced treatment modalities and perhaps more highly trained staff, they do recfuire, in
diOM cases, that the patient be geO^fihiti^y remoVed from the stressis ^teh fomed
the context for the development of his alcohol dependency kl flte-#gt ]^laee, aiid to
which he will be abruptly returned after the conclusion of the fbrmal program.
mm
Disposition of Problem Gases
Most rehabiBta^oii facilities are administered by BuPeK, and sdl approach the problem
according to the principles developed by Alcoholics Anonymous, not the mcdif al model.
Reported recovery rates rise from about 40 percent for the young people wliose atc(jhol abuse
may represent just one manifestation of immaturity or a personality disorder to about
80 percent for career-motivated officers attd enlisted personnel to nearly 90 percent for ijfficei^
in aviation and the Medical Corps.
Medical officers have responsibilities of several types in this program:
1. Helping to develop and maintain an effective, command-level, educational effort
"... devoted to providing factual knowledge about alcohol, drinking behaviors, and
alcoholisTO, including the psycliolog^cad, phygiolo^cal, and administrative consequences
. of the disease"
2. Becoming f alraliar with alcohol reh^iHtation facilities in the local area and determining
if there might be some contribution they might make to the effectiveness of these
programs, and acquainting themselves with the administrative channels whereby
members can be transferred to ARU's and ARC's when appropriate
3. Assisting in a dedicated effort to identify problem drinkers and alcoholics, and working
with the command to insure that rehabilitation appropriate to their needs is provided at
the earliest possible time
4. Insuring tiiat detoxification, if necessary, is accomplished prior to transfer to a
rehabilMation facility, recognizing tiiat most of these have only limited medical support
and are not prepared to manage severe withdrawal reactions
5. i'articipating actively in the follow-up management of the recovering alcoholic by
providing appropriate support directed toward maintaining sobriety, by helping to
develop an enhghtened atmosphere in which he will be able to reassume his former
responsibilities as soon as possible, and by being alert for any early signs of recidivism.
It should be clear that every effort is being made to remove the stigma traditionally
associated with this disease. It is preventable, effective treatment is readily available, and
recovered alcohoUcs can, and do, continue to make very positive contributions to the Navy's
mission and to advance unencumbered throu^ successful careers. Nothing in this Instruction,
however, should be construed as lessening a member's responsibility for misconduct or reduced
effectiveness which might result from alcoholism or alcohol abuse. Furthermore, persons who
fail to benefit from an alcohol rehabilitation program are administratively separated in
accordance with the provision of BuPers Manual Article 3420184 or MARCORPSEPMAN
paragraph 6016 (UnsuitabiUty). Normally, favorably motivated alcohohcs are afforded two, and
only two, opportunities to participate in a rehabilitation program before administrative
processing is effected.
16-21
U.S. Naval Fli^t Surgeon's Manual
BuMed Instruction 5300.4A of April 1977 addresses the disposition of rehabilitated chronic
alcoholic aircrew personnel and air controllers. It directs that such people be considered not
physically qualified for duty involving flight operations while taking Antabuse. Thereafter,
class 2 persoranel may he returned to their flying assignment, with the submission of the report
of a complete aviation physical examination which includes internal medicine and psychiatric
consultations. Class 1 personnel will normally be returned initially to a service group III status
for a period of from three to twelve months, although, in unusual cases, this period of restricted
flying responsibility can be waived. Whenever the individual is returned to unrestricted flying,
the report of a complete examination, including medical and psychiatric consultations, must be
aibmitted. Addttionally, at three-month mtervalg during tiie first year after return to duty from
an flicohd refaalrfitation facility, and every six months for two years after resuming unrestricted
aviation duties, submission of a complete SF 88 to BUMED (Code 5111) is teqilired . .to
insure continuance of their alcoholic recovery state without psychologic and physiologic
complications, "
16-22
Disposition of Problem Cases
SECTION III: AVIATION DISPOSITION
Introduction
What k done with the problem patient — tiie aviator, N,F.O., air traffic controller, or
erJistecl crewmember whose medical problems (1) do not render him unfit for further service,
(2) suggest a possible impSKJt on aeromedical safety, but (3) do not fit neatly into a category
which all concerned agree should change his or her flying status? The purpose of this section is to
assist in determining whether or not there is a problem and, if so, what to do.
Identification of Problem Cases
Whether the evaluation is as casual as a conversation with a pilot in the passageway, or as
formal as a Special Board of Fhght Surgeons, every evaluation performed by a Fhght Surgeon
seeks to answer two questions: (1) Is the individual safe to perform his aviation duties, and
(2) is tiie individual Ukely to remain so in the future? General agreement couM be expected on
the not-physieally-qualified (NPQ) status of the young enaign who suffers a severe unilateral
hearing loss very early in the pilot training syllabus. Disagreement might be expected, however,
about the fate of a lieutenant commander with 14 years of service and several fleet tours who
suffers the same problem. He differs from the ensign in several ways:
1. The Navy's investment in dollars is considerably greater.
2. His experience is obviously ^eater,
3. The aviation experience of the heutenant commander might allow him to compensate
for the defect
4. The future demands the Nasy will make on the individual's services are different. An
ensign in the training command is usually required to be quahfied for all assignments
without restriction; a heutenant commander in &e patrol cflimmunity may fee
comip^tive for the promotion and command assignment even if he is in a permanent
medical Service Group HI category.
Fortunately, there are avenues of assistaiice available in identifying problem cases and in
resolving the problems. The most obvious is close at hand - other Flight Surgeons at the local
activity. In effect, the Flight Surgeon should do what any clinical physician is likely to do with
a difficult patient — seek an independent consultative opinion.
Tlie clinical departments at the Naval Aero^ace Medical Institute can be of considerate
help. Not only do the staffs have speci^zed clinical knowledge, they also possess the historical
experience of previous cases in their clinical field and referrals to the Special Board of Flight
Surgeons.
16-23
U.S. Naval Flight Surgeon's Manual
Finally, there is the Bureau of Medicine and Surgery. Inasmuch as the staff of Code 51 will
make the final recommendation to the Bureau of Naval Personnel/Gommandant of the Marine
Corps, if may be worthwhile to discuss the case with them (preferably with Code 5111) before
much effort has been expended.
There are many situations in which no solution exists on which all can agree. However,
personnel officers will not maintain an aviator in a "limbo" status for an indefinite period
awaiting a definitive decision. The result may be that the ultimate resolution will be reached by
Code 51 at BUMED, acting for the Surgeon General.
Fitness for Duty
The first question to be asked in the evaluation of a problem patient is, "Is jflie iiichnchial
medically suited for continued active service, i.e., is he or she fit for duty?" Normally the
medical lioard action required to resolve this question is the province of the nearest naval
hospital, and i(H advice, both clinical and administrative, should be sought. AfuU discussion of
medical boards and physical evaluation boards is to be found earlier in this chapter. However,
two points should be understood about the finding of "fit" or "unfit" for aviation duties:
1. A finding ol "unfit for duty," whether temporary (limited duty) or permanent,
automatically implies a finding of not physically qualified for all aviation duties.
Although the possibility exists for waiver, to allow an individual on Hmited duty to
continue in flying status under most circumstanees should not be conadered.
2. A finding of not physically qualified for any or all aviation duties in no way implies a
fimiirig of "unfit for duty."
Althougii lh<; two determinations may appear to overlap since a given diagnosis may lead to
findings of both NPQ and "unfit," the two determinations must be considered as independent.
The standards appKed to the determination of "fit" are those of general service. It is relatively
easy to conceive of a situation in which a patient might be unsafe to pilot an atrcraft but safe
medicaUy to serve as a surface warfare officer. That individual would be NPQ for all aviation,
but still '"fit for duty." Although this may seem unfair from an aviator's point pf view, it is not
a matter of service regulation, but rather of law.
Local Board of Fli^t Surgeons
Once a Flight Surgeon has determined that a substantive question exists about an
individual^ fiuitability for continued flight status, but that he or she remains fit for duty,
consideration should be given to convening a Local Board of Flight Surgeons.
16-24
Disposition of Problem Cases
A local board conducts an informal administrative proceeding. Neither formal rules for
procedure mi for "ftie iotm&t of a report are specified, •nor are Aey necessary. Several
considerations should be remembered:
1. The report should be written in a naM-ative formV prefetably ehtonologically. Where a
particulitf body of informatiottls coiEttained itt a: clnies4 ccBimiltatiott or dfherreport, there is no
need to quote lengthy portions of the report. A summary will be suffittifettt, provided the basic
report or consult is included as an enclosure to the report of the local board.
2. Normally the case will be presented by the FUght Surgeon who had primary
responsibility for management of the patient. While it is not necessary for other board members
to examine the patient personally, it is important for the board to meet as a group with the
patient. The patient should understand as much as possible about the medical problem and how
the board feels this impacts flight safety. The patient should be given the opportunity to make
any statement he wsbes ibd to isk questions. TTie patient's written statement, if made, Aould
be included as part of the board report.
3. Once a decision has been reached by the board, the patient should be informed what the
recommendation of the board will be. Although not required by regulation, it is often advisable
to give the patient a signed copy of the final report of the board.
■ ' 4. Although not required by regulation, it is often prudent to submit the report of the
board to the Bureau of Medicine and Surgery via the patient's commanding officer. This is
particularly true when the condition is one in which the impact on flight safety is not
immediately apparent to nooTOeclical personnel, or when the patient disagrees strongly with the
recGirnnend^tipii. ItJtnust be remembered that the patient has certain appeal rights guaranteed
to him by BUMED and BUPERS/Commandant of the Marine Corps. Often these a^ed rights
will be exercised even when the disposition is relatively straightforward to the aeromedical
community, if the patient feels he has not been dealt with fairly and openly. Open discussions
with the patient and involvement of the patient's commanding officer can prevent the wasted
effort associated with the appeal of an obvious recommendation.
5. The report must be complete. Essentially, it must "sell" the recommendation of the
board members. The final recommendation made by BUMED will be formed on the basis of the
report without benefit of examining the actual patient ted without any knowledge of his
cdticHibn not cohts^lted iii thfe teport. If possible, the report stioull he, reviewed by another
flight Itiit^on wlio k tlretoiiKar with the case. If the report does not support the board's
recommendation ^ that reviewer, it is unlikely to do so to the persotmel in Code 51 at
BUMED.
16-25
U.S. Naval Flight Surgeon's Manual
Xinfortunately, many of the conditions that result in the convening of local boards lead to
temfcatiott^of flight statosi Wmatd mtsMmts should always keep in mind that their action will
have m^Mcmt impmt on fkt future of the patient. Revoeation of fl^t *tatus means a
decrease in pay, a significant change in life plans and career pattern, TOllfre^lBmlfy, a. dainaging
blow to self-esteem. Board members should also be mindful of the fact that all aviators in the
local area may feel threatened by the board's action. Therefore, the action of the board must
not only be medically correct, it must be managed in a way that is understandable by the line
community.
Special Board of FB^t Sni^eons
Occasionally, a case will arise that, due to its complexity or its uniqueness, warrants referral
to the Special Board of FU^t Surgeons (SBFS) at the Naval Aerospace Mescal Institute
(NAMl), JPensacolst, Elotida. The initial recommendation to refer to the SBFS can be imde by
anyone (including the patient or his command), but the final recommendatioai for iefe«fld can
be made only by the Bureau of Medicine and Surgery. Personnel attached to the Naval Aviation
Training Command may be referred directly to the SBFS upon consultation with the
conimmiding officer of NAMI. Normally, BUMED will recommend SBFS referral to the Chief of
Naval Personnel/Commandant of the Maria© Gorps, who witt then dirrast the patient's
commanding officer to order Uie patient to NAMI for evaluation by the SBFS. Unless the
patient's commanding officer has made special arrangements with the Commanding Officer of
NAMI, no patient should be sent to Pensacola prior to receiving official notification. This
prevents unnecessary referrals, or referrals when NAMI is not prepared to evaluate the patient.
The SBFS Vfas established to provide comprehensive evdii^bhs c>f ' ^|:^clilt i^rbli^etilical
prohleins, JsareitrictBd by the time and schecliO^' feonirt^mnis f(»i^iid at'ciMM *fetttem.
Regardless of the presenting complaint, the patient is evaluated by all major departments at
NAMI. During his evaluation, he may be assigned a counselor and advisor. This individual does
not vote on the board's final recommendation. Following the completion of the evaluation, the
patient is presented to the SBFS, his problem is discussed, and a recommendation is formulated
(with minority report(s) if indieated) for forwarding to the Bureau of Medicine and Surgery.
The Special Board of Fhght Surgeons consists of all designated naval Flight Syrgefiijm iJJ ^e
Pensacola area, with the Commanding Officer, NAMI, as the senior member. The mtent is to bring
the maximum aeromedical experience to bear on specific cases. Normally, the evaluation begins on
Monday with presentation to the board on Friday of the same week. Although rarely necessary, the
Commanding Officer of the Institute has tiie authority to extend the evaluation as he feels impro-
priate or to refer the patient elsewhere for evaluation prior to presentation to the board.
16-26
Disposition of Problem Cases
The recommendations of the SBFS are forwarded to BUMED for endorsement. Although
normally forwarded to BUPERS/Commandant of the Usame Corps for implem^tation without
change, BUMED has the prerogative to modify or reverse the recommendation as is felt
appropriate.
No prior limits are placed on recommendfttiorai that can be made by the SBFS. Although
the board will normally attempt to fit its recommendation into feasible persoimel alternatives,
the board is specifically not constrained by any published standard or restriction.
The Board of Fli^t Surgeons at the Bureau of Medicine and Surgery
The Manual of the Bureau of Naval Personnel guarantees an appearance before a board of
Flight Surgeons to every designated naval aviator or naval flight officer who is in danger of
having his flight status revoked for medical reasons. The intent of this guarantee is considered to
have been met when a patient appears before a Local Boanl or Specisd Bomd of Flight Surgeons,
or when action is taken on the basis of a sin^-phydcian fli^t physical without the patient
requesting appearance before a board. Oli oCcasjon, a paliettt whose flight status has been
revoked or limited will formally appeal the medical recommendation. The Chief of Naval
Personnel/Commandant of the Marine Corps will then direct that the case be considered by the
Board of Flight Surgeons at the Bureau of Medicine and Surgery. Where appropriate, a personal
appearance by the patient before this board may be authorized.
This board is formally appointed by the Chief of Naval Personnel, and it is, in effect, the
"court of last resort." Normally, the patient will be ordered, on no-cost orders, to the National
Naval Medical Center, Bethesda, Maryland, for any additional specialty evaluation felt to be
indicated by the senior member of the board, tiie Directot of Aerospace Medicine at BUMED.
The specialty consultant is normally invited to sit with the board as an advisor, but does not
vote on the final recommendation. The board, consisting of at least five members, of which at
least three must be Flight Surgeons, hears the case, interviews the patient, and votes on a
recommendation. This recommendation to the Chief of Naval Personnel is considered to be final
and is not subject to further appeal.
Condusion
As with any clinical specialty, difficult cases represent the ultimate challenge to the dis-
cipUne of aviation medicine. The challenge to find the right "answer" to a difficult aeromedical
problem is much greater than is normally found in clinical medicine, due to the complex inter-
actions of non-medical factors. A Fhght Surgeon confronted with a difficult aeromedical prob-
lem should seek assistance, and seek it early in the process, from feflow Flight Surgeons, from
clinical departments at NAMI, and from personnel in the Aerospace Medicine DivisioB. at
'lUMED.
16-27
U.S. Naval Flight Surgeon's Manual
APPENDIX 16A
MEDICAL AND ADMINISTRATIVE DISPOSITION CHANNELS
Medical Channels : (Office of Naval Disability Evaluation)
Any disease or illness^
(including psychotes-
and neurons)
FpEB PDRB
(DESC)
— ~* Hospital;;
' (BUIMEDINST
' 1910.2G) '
I I
\ I
'-Medical (DESC)
Bbard -
1-
►CPEB-
(DSM)
PRC — *>JAG -^ SECNAV
(Ch. 18, MMD)
(refer) (RBcoininflnd) iReview) (Review) (Decide)
Administrative Ghannefs:
Any disorder or defect Cornmand-^ Administrative Processtng
Personality Disorder-
-- BU MEDINiT igi0.3B of 24 Aug T976
BUMEDINST 19T0.2G of 26 Aug 1975
BUPERSM AN ART*'^20184
BUPERSMAN Afit
BUPERSMANART 3850100
BUPERSMAN ART 34101Q0
SECNAVINST 1920.6
Chief of Naval
Personnel
(or)
Commandant of
the Marine
Corps
(Officers)
Convenience of the
Government ^ BUPERSMANART 3850220
BUPERSMAN AHT SI50220, Paragraph 5
BUPERSMANART 3420270
BUPERSMANART 1860120
BUPEF^MAN ART 38ia220
Marginal Performers
Good of 'tiie Service — «■
Conscientious Objection
Alcoholism SECNAVINST 5300.20 of 18 May 1972
OPNAVINST 6330.1 of 29 May 1973
BUMEDINST 5300.4A of 19 April 1977 (Aviation)
BUPERSMAN ART 3420184
Drug Abuse and Exemption
Program SECNAVINST 5355.1 A of 5 March 1975
BUPERSMANART 3830360 (Officers)
BUPERSMANART 3420183 (Exemptee)
BUPERSMANART 3420185
Homosexuafrty SECNAVlNSf T9bO,9A of 31 July 1972
Class 1 Court Martial or BUPERSMAN ART 3420185
Class 1 1 ■■ BUPE RSM AN ART 34201 85 or Court Martial
Class III BUPERSMANART 3420184
Class IV BUPERSMAN ART 3420185
Appeal, either "full and fair" or "prima facie".
For Marine Cci ps Separation Manual paragraphs which correspond to SUPERS Manual Articles, sae table at beginning of thi
chapter.
16-28
V
17
o
CHAPTER 17
AEROMEDIGAL EVACUATION
Introduction
Military Airlift Command Aeromedical Evacuation System
Humanitarian Aeromedical Evacuation
MAC Aircraft and Facilities
The Flight Surgeon's Interface witibi MAC Aeromedical Evacuation System
Factore Aff iecting the Air Transport of Patients
Patient Acquisition
Triage
Early Treatment
Intratheater Transport
Intertheater Transport
References
BibUography
Introduction
The first medical evacuation by air occurred in 1870 during the seige of Paris when a total
of 160 patients were removed from the city by observation balloon. Itt 1915 during the retreat
m Serbia, an airplane was used for the first time in the eiratmation of cai^alties when twelve
wounded men were flown from the battle area in unmodified service-type aircraft. The French
instituted the first airplane ambulance organization under the direction of Major Epanlard
consisting of six airplanes each configured to carry three litter patients. These airplanes
evacuated more than 1200 patients from the Atias mountain area during tiie Riffian War m
Morocco*
In 1919, the Royal Air Force of Great Britain first transported casualties by placing
stretchers inside the fuselage of a DH-9 airplane during the war against the Mad Mullah in
Somaliland. And in 1923, some 359 patients were transported in Kurdistan.
Captain George Gosman, MC, U.S. Army, constructed an ambulance airplane at Fort
Barrancas, Florida in 1910. A request for additional funds for further development of this
aircraft was denied by the War Dfepsurtmetlt. At Gerstner Field, Louisiana in 1918, Major
Nelson E. Driver, MC, U.S. Army, and Captain William Ocker of the American Air Service
17-1
U.S. Naval Flight Surgeon's Manual
converted a JN-4 airplane into an ambulance by modifying the rear cockpit so that a special
Itter coiild be earned. During the next several years, ambulance aircraft were used by the
tJ.S, Army on an emergency basis only, d^pite repeated u^ngs by Army Medical Corps
officers for the routine use of transport airplanes for evacuating casualties in the event of war.
It was during the Spanish Civil War (1936-38) that evacuation of casualties by air first
occurred on a large scale. The Germans transported the sick and wounded of their Condor
Legion from Spain to Germany iji JU-52 airplanes, each of which was configured to carry six to
ten Utter cases and two to eight amhulatory cases. The route flown was across the
Mediterranean to northern Italy, crossing the Alps at altitudes up to 18,000 feet. Thje total
distance traveled varied between 1,350 and 1,600 miles with an elapsed air time of about ten
hours. Oxygen was available and used while crossing the Alps, but the extreme cold at higher
altitudes was a major difficulty because the planes were not equipped with heating systems.
Soon after the onset of World War 11, an organized system for the air evacuation of
wounded was instituted by most of the warring nations. Medical air evacuation squadrons were
formed and a school established for their training in 1942 by the United States Army Air Corps.
Patients were transported by troop carrier aircraft within the various overseas theaters, but the
return of patients to CONUS was carried out by the Air Transport Command. By the end of
World War U, the United States Army Air Corps had transported over a million and a quarter
patients.
The Korean campaign of 1950-51 saw the introduction of the helicopter as a primary air
evacuation aircraft for the movement of casualties from the battlefield to the initial point of
treatment. Hie hehcopter also began to assume greater importance in the transfer of patients
from smaller ships to well-equipped attack Garriers. By 23 February 1954, the U.S. Air Force
Military Air Transport Service had transported its 2,000,000th patient.
During the Vietnamese conflict, full exploitation of the helicopter for battlefield pickup of
casualties, together with the rapid transport of the wounded to definitive treatirienl centers by
jet-engined air evacuation aircraft, permitted a further reduction in mortality of the \^founded.
In World War II, the mortality rate among casualties reaching medical treatment facilities was
approximately four percent. The rate was reduced to near two percent in &e Korean conflict,
and in the operations in South Vietnam, it was further reduced to approximately one percent.
Military Airlift Command Aeromedical Evacuation System
A cost-effectiveness study was completed following World War II to determine the relative
merits of moving patients from overseas back to CONUS by water and by air and within
17-2
Aeromedical Evacuation
CONUS by rail and by air. Not only was it found that it was mor© toneficial to the paJifnt to
move him by air, but the attendant savings in time, as shown in Table 17-1, mmM in ni«e
effective utilissation of crew m^beiB and trained medical personnel. Accordingly, on
7 September 1949, the Secretary of Defense directed that the evacuation of sick and wounded
military personnel would be accomplished by air both in peace and war. Hospital ships and
other surface transportation might be utihzed to move patients if deemed necessary in unusual
circumstances. That policy is reiterated in OPNAVINST 4630.9 series whfeh States ia addition
that aeromedixsal evacuatiofl wiU |e petforpsa .«>«t^ftoy limits ^eeifeaUy assigned that mission.
If a commanding officer and the MedW Officer determine that the medical urgency is such
that time involved in securing aeromedical evacuation service will likely endanger the life, limb,
or cause a serious compUcation resulting in permanent loss of function by the patient, then
aathority for use of local aircraft is vested in the base commander. This exception is defined in
Department of Defense Regulation 4515.13-R which is contained as an enclosure to
OPNAVINST 4630.25 series.
Table 17-1
Transportation Times ,. ,
Hospital Ship vs. Aeromedical Evacuation
To U.S.
From:
WWI
WWII
Korean
War
Present
Europe
No Patients
Returned to
U.S. Until End
of WW!
26 Hours
Flying Time
Ship-10 Days
7 Hours
Flying Time
Ship-10 Days
Japan
32 Hours
Flying Time
Ship-21 Pays
32 Hours
Flying Time
Ship-21 Days
9 Hours
Flying time
Ship-21 Days
Korea
36 Hours
Flying Time
Ship-21 Days
10 Hours
Flylntg Time
Ship-21 Days
S. East
Asia
40 Hours
Flying Time
Sliip-21 Days
40 Hours
Flying Time
Ship-21 Days
13 Hours
Flying Time
Ship-21 Days
(Funsch a Hankins, 1966, printed by permission of Resident Physician).
The Department of Defense has assifned the mission of providing aeromedical evacuation
service for the United States armed fortes to the Air Force Mihtary Airlift Command (MAC).
17r3
U.S. Naval Flight Surgeon's Manual
Accordingly, MAC operates a world-wide network of aeromedical flights and support activities,
fhe glofcal Sfitem t^aft J»e didded ante titteie area% each Ms dwn command post. The
do Aestio '^te*, ^Mch toillideg CQTOS^ §aribhean and (Northeast Atlantie aa-eas, and Alaska,
has its command post at Scott Air Force Base, Illinois. Within the domestic system, there are
two types of scheduled aeromedical flights - "trunk" and "feeder" lines. Both lines are
supported by flights operated by seven MAC aeromedical units located at Scott AFB, Illinois,
LbwryAFB, Colorado, Travis AFB, California, KeUy AFB, Texas, Maxwell AFB, Alabama,
Andrews Ai'ftj I^S^ia, ant McGuire AFB, New Jersey. "Trunk" line atreraft fly regularly
sehedtalfed;,' ttiiii-iStop tripi between the seren aeroinedidal units. Within the area served by each
aeromedical unit, "feeder" flights pick up and deliver patients at military hospitals. The overseas
system has command posts at Hickam AFB, Hawaii, for flights in the Pacific fmd at Rhine-Main
Air Base, Germany, for flights in the Atlantic area.
Humanitarian Aeromedical Evacuation
For the purpose of air transportation eligibility, DOD Regulation 4515. 13R divides patients
into U.S. armed forces and non-U.S. armed forces categories. U.S. armed forces patients include,
by definition, an active duly or eligfbfe ne&ed membier of a Military Department; a dependent
of a member of the miUlary on active duty ot of a member deceased while on active duty; a
dependent of a retired or deceased, retired member of the military wjbo is autliomed medical
care under the provisions of SECNAVINST 6320.8; and a U.S. citizen civilian employee of the
Department of Defense and his lawful dependents when stationed outside CONUS.
Emergency lifesaving aeromedical transportation is authorized for non-U.S. armed forces
patients only upon satisfying the following criteria:
1. The patient's illness or injury is an inunediate threat to life.
2. The patient is situated where medical capabilities for adequate diagnosis and treatment,
.under generally accepted medical standards, are not available in the immediate
geographical area. In these cases, transportation will be fiimished only to the nearest
medical facility which can provide the necessary treatment.
3. Suitable commercial transportatiori is not available.
Non-U.S. armed forces patients will not be acceptable for movement if their condition is
terminal, or if the only reasons for the request for mihtary tran^ortatioii are lack of personal
funds, personal or famUy convenience, or medical experimentation (unless determined by
competent medical authority that such experimentation will save life).
17-4
Aeromedical Evacuation
MAC Aircraft and Facilities
MAC currently operates a fleet of high-performance jet aircraft throughout its global
aeromedical evacuation network. In the domestic and European systems, the C-9A Nightingale
(Figure 17-1), which is a C-9 permanently configured for patient transportation, is the most
recent iWfcraft in the inventory. For movement of patients from overseas to COISfUS, Ae
C-141A Lockheed Starlifter (Figure 17-2) has replaced the C-135B Boeing Stratolifter. The
G-14li like other military cargo aircraft, has the distinct advantage that, following delivery of
cargo to an overseas destination, it can be rapidly reconfigured for patient trsgisportation.
Figure 17-1. Interior of C-9A Nightingale configured for patient transportation
(U.S. Air FofCiB ph£»tograpK),'
Figure 17-2. C-141A Starlifter (U.S. Air Force photograph).
17-5
U.S. Naval Flight Surgeon's Manual
At selected sites along the air evacuation routes are Aeromedical Staging Facilities. These
medical facdities provide reception, processing, ground transportation, feeding, and limited
medical care fra- patients entering, en route, or leaving die aisromedical evacjiation ^stem-
similar in' function but moje highly inohde is a Mohile Aer omedicfil Staging Facility for use in a
combat zone.
Inasmuch as possible, MAC will meet the following criteria in providing aeromedical
evacuation services:
1. Movement of patients from aerial ports within CONUS shall be no later than 36 hours
after arrival,
2. Patients ;^al]L;|!§ delivered to destination wiibte 72 hoMW sitet mtxf Mth the domestic
system.
3. There shall be an average of not more than one overnight (RON) stop between the point
of entry into the domestic system and dehvery at destination.
4. An RON stop shall not exceed 36 hours.
5. Time in transit shall not^ exceed 18 hours prior to an RON stop for rest and
recuperation.
Flight Surgeon's Interface with MAC Aeromedical Evacuation System
OPNAVINST 4630.9 series distinguishes various types of aeromedical evacuation flights
based in part on their origin and destination. Domestic aeromedical evacuation is that phase
which provides ^§^t- %r patients between points within CONUS and from near offshore
installations. Intertheater aeromedical evacuation is that phase which provides airlift for patients
from overseas or from theaters of active operations to CONpS. hfifrafheater evacuation is that
phase which provides airlift for patients between points of treatment outside a combat zone but
within a theater of operations. Tactical evacuation flights provide airlifts for patients within and
from a combat zone to points outside the combat zone. Forward aeromedical flights are limited
to airUfts for patients between points within a battlefield and from the battlefield to initial
point of treatment and to subsequent pomts of *"eatment within the combat zone. However,
over routes solely of interest to the Na^ (including *he Msuine Corps), and where facihties of
the Air Force cannot provide the service, the Navy OVerieas commander is responsible for
aeromedical evacuation.
Within the Umits of the preceding definitions, the types of aeromedical evacuation with
which the Fli^t Sui^eon is coueemed, are the forwar^, tactical, and on certain occasions,
intratheater flights. These terms have Utile relevance to the aircraft carrier or LPH or LHA ai
17-6
Aeromedical Evacuation
sea, and the primary concerns of the Flight Surgeon outside CONUS are acquisition of the
patient, early treatment, and evacuation to a hospitiH or MAC aeromedieal evacuation flight.
Facton Affecting &e Air Transport of Patients
Any decision to evacuate a patient by air constitutes a major value judgment. It should be
arrived at only after a thorough asaeSSinent of the raedical beneflts for tiie patient as opposed to
the hazards which mi^t be assoeialed - witih an evaGuation fl^t. Prerequisite to this
de<cision*inaldttg pwjcess is an in-depth understanding of the risks unique to patient trani^Ft %
air, their possible interaction with the patient's condition, and their influence on en tOttt®
treatment modalities.
There are no absolute medical contraindtcatiom to aeroniedieal evacuations Much can be
done by the Fli^t Surgeon to achieve a medically successful flight by minor manipulations of
the patient's environment dtttiOg the evacuation or by preparation of the patient to better
withstand the en route risks. An example of the former would be the recommendation of a
specific flight level in an unpressurized aircraft or a particular pressurization profile in a
pressurized aircraft for the evacuation of a case of dysbarism. Or, in certain traumatic cases, a
carrier deck launch of the C-IA evacuation aircraft mi#it be indicated rather than a catapult
lajmeh. Resuscitation and gtsObil^tion of the patient prior to evaeuation cannot: be
overemphasked, for these plinc^iles more than any others influence the final therapeutic
outcome. On occasion, it may even be wise to delay the evacuation in order to stabilize the
patient because spatial limitations, light, noise, or other en route environmental conditions
either preclude or make routine monitoring and therapeutic procedures extremely difficult.
It is beyond tiie scope of this section to consider in detail the effects of altitude on all
medical and surpcal conditions for which aeromecfccal evaeilation may be indicated. However,
certain general principles applicable to all patient movement by air transportation will be
outlined, together with some of tiie conditions requiring special management.
General Risks
Decreased Atmospheric Prewtre. Chapter One describes the physiological effects of
decreased atmospheric pressure. Although all scheduled MAC aeromedical evacuation flights are
in pressurized aircraft, the Flight Surgeon may have occasion to transport patients aboard
unpressurized aircraft. Even in pressurized aircraft, cabin altitudes of 7,000 feest ttay M
encountered, and the possibility of rapid deeomprestfOii must be kept in mind. With a redUiCstfdtt
in barometric pressure, gases present within the body tend to expand iti aocordanfee with Boyle's
17-7
U.S. j\aval Flight Surgeon s Manual
law, and, if unable to escape, may mptBiTe th© containing walls of the cavity in which they are
trapped or impair cirQulation by eiierti% f |^ur« on thenyalte ti5MnMy^^^^ surrounding
tissue.
Decreased Oxygen Tension. A concomitant decrease in oxygen tension occurs with
diminished atmospheric pressure. Although oxygen saturation of hemoglobin is only slightly
diminished' at edte: alMtatfes^tft pressurized afrcraft and in flights below 10,000 feet in
unpregffliri^dlvaiBeisaft, such a reduction may be critical in patients whose oxygeftatibtt of vital
tissues ^.ni^nal for any reason even at sea level. Conditieng m whlfeh this could be a factor are
anemias, recent acute blood loss, impaired pulmonary flinction, cardiac failure, organic heart
disease, or sickle cell trait.
Dehj^mMon. The relatit& humidity at altitude in both pressurized and unpressurized
afeciaij iS iS^^ reduced. Dehydration may represent a risk to the unconscious or
iHM'gbially hydrated patient. Patients with tracheostomies or those who must breathe through
their mouths may require humidified air or oxygen to prevent drying of respiratory secretions.
Corneal drying in comatose patients may be averted by closing the eyelids and holding them in
that position with mo istened cotton pads under eye shields.
MoAon Sickness. The incidence of motion sickness in large jet aircraft flying at altitude is
low. However, in helicopters and sMall aircraft- opwating at lower altitudes and off carriers,
motion sickness is more frequently encountered. In some patients it may be prevented by the
administration prior to flight of one of the antihistamines (25 to 50 rM<i meclizine, 50 mg
cyclizine, or 50 mg dimenhydrinate) or "scopodex" (0.6 mg scopolamine with 10 mg
d-amphetamine).
Fatigue and Inactivity. The ambulatory patient is soiSiefSlheg placed on a non-MAC flight
whose primary mission is operational rather thaii aeromedical. Li troop transport aircraft, the
crowded seat configuration may discourage the patient from moving about during flight. The
enforced inactivity together with the anxiety and apprehension associated with illness may
result in a much more pronouiifced state of fatigue than would be expected.
Ckmditions Requiring Special Management ' "
Cardiovascukr Blness. Patients with recent myocardial infarctions or anginal symptoms
mmt be t^yalnatecl im a case-by-case basis prior to evaquatiori. Supplemental oxygen
should be available ,iijrt^t*. flflyd ¥i8^ drugs should be ppoi^ded those patients with
angina pectoris who experience symptoms during flight. Cabin altitude or flight level
should not exceed 6,000 feet. For patients in failure or with a history of any myocardial
17-8
Aeromedicid Evamaticai
infarction within eight weeks of the acute episode, the American College of Chest
Physicians recommends that a cabin altitude of 2,000 feet not be exceeded.
Pulmonary Disorders. In patients with artificial, traumatic, or spontaneous pneumothorax,
movement bv air should generally be deferred until there is radiographic evidence that the gas
has been absorbed. However, if the volume of gas remaining is small, restriction of altitude may
enhance safe movement. Chest tubes may be left in place, but the Heimlich Valve must be
applied. Patients should aot be airlifted for 72 to 96 hours after chest tube removal, and a
roentgenogram should be obtained within 24 hours of the flight to estabUsh that the lungs have
remained fully expanded.
Anemias. Patients with severe anemia or recent acute blood loss should ordinarily have a
hematocrit of not less than 30 mg percent prior to entering the aeromedical evacuation system.
Hematocrit should be checked within 36 hours prior to flight. In patients who are known to
exhibit the sickling trait, the presence of an acute infectious process Under conditions of
reduced oxygen partial pressure may precipitate sickling crisis manifested by sicklemia,
vomiting, and left upper-quadrant pain.
Gastrointestinal Disorders. Large unreduced hernias, volvulus, intussusception, and ileus are
particularly susceptible to trapped-gas phenomena, and the circulation of the involved bowel
loop may be severely compromised as a r^lt of expandon of trapped g«s. Air traisiport of
these patients should usually be deferred until after definitive therapy and recovery, but if
movement is mandatory, it can usually be accomplished safely if altitude is restricted. It is
conceivable that weakened viscus walls in peptic, amoebic, typhoid, or tuberculous ulcers would
be unable to withstand the pressure of gas expansion, and the involved portion of the
gastrointestinal tract would rupture. Disruption of a ajrgical incision postoperatively due to
intra-abdominal gas expansion is a threat, and a ten-day period of convalescence and wound
healing is often recommended prior to airlift of the patient. Colostomy patients evacuated by
air require an extra supply of colostomy bags and dressings.
Orthopedic Patients. Casts should be clearly marked with the date of application and the
nature of the fracture or the surgical procedure which was performed. Very recently applied
casts should be bivalved to allow for soft tissue swelling at altitude. It is preferred that plaster
casts be allowed to dry for 48 to 72 hours prior to airlift of the patient. Traction devices
utilizing swinging weights are unsuitable for use in flight from the standpoint of both efficiency
and safety. The Collins traction device is the only acceptable alternative, and it must be
provided by the originating activity. It is an extremely effective spring tension apparatus which
may be used to provide spinal traction as well as traction to the extremities. Paraplegic patients
17-9
U;S. Naval Flight Surgeon's Manual
are generally moved on a Stryker frame to facilitate care and comfort during the flight. It is
important that tjle lentire fraine accompany the patient since parts from various frames are often
not interchangeable.
Eye Injuries and Diseases. A common injury to the eye necessitating aeromedica! evacuation
is perforating trauma of the globe. Because the eye is normally a liquid-filled organ, it is not
affected by barometric pressure changes. But once the globe is surgically or traumatically
opened, air may be introduced inteiitionaUy or as a result of the injury. In such instances, a low
cabin altitude must be maintained in order to prevent the air from expanding and pogmbly
re-opening the wound or separating the surgical incision. In patients having choroidal or retinal
disease or injury, it should be recalled that the retina has the highest oxygen demand of any
organ in the body. Therefore, oxygen should be administered to the patient at altitudes greater
than 4,000 feet.
Ear, Nose, and Throat Conditions. In many patients who are being airlifted for other
reasons, an incidental diagnosis of upper respiratory infection is made. Development of barotitis
media and barosinusitis may be forestalled by administration of decongestants prior to the
flight.
Skull Fracture. Any patient with a skull fracture which extends into a paranasal sums, bony
ear eanal, or middle ear must be carefully examined by x-ray to rule out the possibihty of air
having been introduced into the cranial cavity. Should it become necessary to aeromedieally
evacuate the patient prior to absorption of the air, flight altitudes must be severely curtailed or
cabin pressure maintained as near sea level as possible.
Mandibular Fracture. Commonly, mandibular fractures are wired so tiiat the mouth may not
be opened. Should the patient become airsick, he may be at risk to suffer a massive aspiration of
vomitus. If aeromedical evacuation is anticipated, the patient's upper and lower jaws will be
immobilized using tie elastic hands. An emergency release mechanism must be provided which
can be activated by either the patient or attendant. Unless the patient is a Class lA or IB patient
(psychiatric Utter patients requiring restraints and/or tranquilizers) or under guard, he should
have a pair of scissors attached to his person.
Patient Acquisition
In order to insure clarity of presentation, the acquisition and management of patients
aboard eariiers, LPH's^ LHA's, and smaller ve^els at sea has arbitrarily been divided into five
phases (Figure 17-3). This permits an orderly discussion of these matters, despite the fact that
one phase may overlap or progress into the next without interruption. In those instances where
17-10
Aeromedical Evacuation
multiple casualties occur simultaneously, their management is rarely so orderly or deliberate.
Nevertheless, such divipions do permit a better understanding of the progressive stages in
management and illustrate the chronology of the decision points.
PATIENT ACQUISITION
Aircraft Carrier
EmOTgency First Aid
Selection of Stretchers
Selection of Route
Prior Training and I nspection
Other Vessel
EmergencY Treatment
Radio Consultation
Selection of Transfer Method
Highlirie
Stretcher
Bosun's Chair
Helicopter
Small Boat
TRIAGE
Establish Working Diagnosis
Determine Priorities for Care
( ^ EARLY TREATMENT
Air Transportability
Evacuation Decision
Communications with MAC
Emergency Treatment
INTRATHEATER TRANSPORT
Patient Preparation
Transport from Sickbay and Aircraft Loading
Emergency Patient Care En Route
Holding Facilities at Transfer Point
Patient, Records, and Property Transfer
INTERTHEATER TRANSPORT
MAC Aeromedical Evacuation Flight
Figure 17-3. Phases in acquisition and handling of casualties at sea
(adapted from VS. Naval Flight Stifgem's Manuals, 1968).
Aircraft Carrier
When a casualty occurs, shipmates should give immediate first aid to the victim and notify
the medical department. However, first aid may not always be rendered because of lack of
17-11
U.S. Naval Mi^t Surgeon Manual
expertise or fear of making the injury or illness worse. Adequaey of first aid performed by
members of the crew is often an index of the success of the ongoing first-aid training program
by the ship's medical department. Confusion is often present, and there sometimes is delay in
informing tlie medical department. In many cases, notification to sickbay consists only of a
request for a corpsman, with no information furnished as to the nature and extent of the injury
or illness. Location of the casualty should be given by frame number, section, and compartment
number. The hospital corpsman may arrive before the medical officer and begin first-aid
treatment. Corpsmen bring a first-aid bag and a resuscitator to every emergency call on the ship.
If there Ls a disaster such as fire or explosion, the corpsman and medical officer must stay
clear of repair parties fighting the fire or other damage and limit their efforts to care of the sick
and wounded. The repair party is trained and equipped to perform rescue operations, and such
operations are not witMn the purview of the medical department unless directed by competent
authority. In a disaster in which a number of repair party personnel are injured or killed, all
medical department members of the nearest battle dressing station may be required to perform
rescue operations in addition to caring for the injured. Every possible effort must be made to
control hemorrhage, maintain adequate airway, and minimize further injury during the rescue
process.
When first aid has been administered, the casualty must be transported rapidly to sickbay in
such a way as to minimize the possibility of further injury pr a^avation of existing injury. To
achieve these goals, the medical officer or hospital corpsman must select stretcher type and
evacuation route to sickbay.
The three types of stretchers available aboard ship are the Stokes, the semirigid (Neil-
Robertson), and the field (pole Utter). The Stokes stretcher is 9 wire basket with a tubular
frame, contoured to give support to the occupant and to keep the frame between the patient
and possible impacting objects. It has a wooden slat frame in the torso section, lines attached at
head and foot for lifting, and straps at torso and midleg to keep the patient within the stretcher
despite considerable movement. It has been widely used throughout the Navy for years. The
prime advantage is that the frame of the stretcher itself tends to prevent further injury and the
aggravation of existing injury. It is light and strong and almost always readily available. In most
cases, once the patient is in a Stokes, he can be transported directly to sickbay, given prelimi-
nary care, transported to the flight deck, loaded onto an aircraft, and transported to the facility
which will render definitive care — all without transferring him from the original stretcher.
The Stokes is excellent for higUine transfer when equipped with proper flotation equipment
and protective frame, as shown in F^re 174. A major disadvantage, however, is that once the
17-12
AeromedKcal Evacuation
patient is properly strapped in, it is difficult for him.ttf get out of the stretcher or even to free
his arms. In the event that he goes into the water, either on highline transfer or in a crash while
being evacuated by aircraft, he is thus unable to swim or help himself in any way. Some
protection must therefore be provided in the form of flotation equipment (in highline transfer)
mi/w an attendant (on over-water flights) who can assist the patient in emergency escape.
lt-4, Highline tranafer of a patient in a Stokes stretcher
(tJ.S. Navy photograph).
17-13
U.S. Naval W^t Su^eon's Manual
The semirigid stretcher is specifically designed to allow the patient to be packaged in the
smallest possible volume so that he can be moved through restricted openings with speed and
facility. Greater care must be utilized in transporting a patient aboard ship in a semirigid
stretcher" because the stretcher itself provides little, if any, protection, and it does little to
prevent a^avation of existing injury during transport, advantages of the semmgid are that
it can be used in spaces where the Stokes wiU not fit, and it can be Ufted vertically as through an
escape trunk. It is the stretcher of choice in patient evacuation from or through confined spaces
and restricted passages.
The field stretcher or pole litter is cairied aboard ship primarily for use by the Marines
and/or landing p»ady. It occupies ,Iess floor space than a Stokes and gives greater external
protection than a semirigid. However, it is inadequate for patient transportation from confined
spaces. It is the stretcher that must be used for MAC flights, and, when a minimum number of
transfers from one stretcher to another is desired during aeromedical evacuation, it should be
utilized originally in evacuating the patient from the ship. If, however, the patient is to be flown
from the carrier, the Stokes stretcher is preferred because the patient can be better restrained
during the accderation stresses of a catapult launch*. With tire HilW iiitcher, an air mattress
must be used to give comfort compatible to that of the Stokes.
Location of stretchers aboard ship is clearly deUneated in the Battle BUI which must be kept
up to date by the Medical Officer. Periodic inspections under the supervision of the Medical
Officer are necessary to insure that aged or missing handling lines and straps are replaced, that
stretchers are in their designated locaiiO|is, aitilllat they are in usable condition.
The evacuation route selected for the patient often determines the stretcher type to be used.
In cases of disasters or battle damage, routing for a patient from a particular area to sickbay
must be obtained from Damage Control Central (DCC). This unit is informed of the location
and extent of all damage and is therefore able to select an evacuation route deigned to avoid
the hazard of injury to patient or crew while retaifl^ maximum waterti^t integrity of the
ship.
An aircraft elevator is a safe and expedient method for transporting a litter patient to
sickbay following an accident on or near the flight deck. Weapons elevators may be used in
i rnergencies and offer the additional advantage of direct access to the second deck, thereby
eliminating the requirement to transfer the patient from the hangar deck to the second deck.
Keystones in successful management during the patient acquisition phase are training and
inspection — (1) basic and refresher first-aid training of the entire crew on a continuing basis by
tiie ship's medical officers and hospital corpsmen; (2) disaster training for ike medical
17-14
AeromediGal Evacuation
department, including the teaching of evacuation routes and disciphne at the scene of disasters;
and (3) routine scheduled inspections to insure the reliability and availability of emergency
equipment. The Medical Officer, the Flight Surgeon, and the medical department must be
thoroughly prepared prior to the battle or disaster.
Other Vessel ' ^'
tiy virtue of an attack cktriei's" relatively largfe' medical diepartment and greater treatment
capabilities, the deployed Flight Surgeon is not only active in the treatment of illnesses and
injuries that occur aboard the carrier, but he often may be involved in providing consultation
services and/or treatment to patients from other ships or shore facilities. Most commonly, such
requests for medical aid come from smaller ships steaming in company. On occasion, however,
they may arise f rolii ' disf aiit ship's, merchant tiiariii^ vessels, pid shofe StatiomJ The
patients can often he treated definitively iantl ristiimeci'to the referring activities fit for full duty
without the need for further transfer to a hospital. Injuries occurring on small vessels usually
receive first aid from other crewmembers, particularly if more than one casualty is present. The
role of training is, therefore, fully as important as aboard a carrier.
Once first aid has been given and the patient evacuated to a suitable space where a medical
department representative can examine and care for him adequately, his gross status must be
determined - bones broken, pale or clammy skin, open wounds, etc. Ir^ eases of acute illness,
the medical department representative obtains a history of present illness, examines the patient,
and performs any laboratory studies which mai^ be indicated and for which he possesses the
capability. , .
The medical department representative then arran^s a cungultatlon witii a medical, officer
on the nearest naval vesseL Once radio contact is establishedj thi consultation may proceed by
two-way voice communication, teletype conference, or message. (For this example, it is
assumed that the casualty is aboard a destroyer which is in proximity to an aircraft carrier.) The
medical officer's immediate concerns are assessment of the patient's condition, establishment of
a working diagnosis, formulation of a treatment plan, and a decision as to whether the patient
requires evacuation to ihe eanrier.
If the medical officer recommends transfer of the patient to the carrier, he should at that
time recommend a mode of transport so that the commanding officer may consider the risks
and the alternatives. Any such transfer at sea entails risks to one or both vessels, to their crews,
and to the casualty. It is the medical officer's duty to assist the commanding officer by
(1) ohtaioing as many facts about the pa^iient as po^ihl^ during the risdiq consultation,
(2) making as careful a differential diagnosis as possible, with an estimate of liie
17-15
U.S. Naval Flight Surgeon's Manud
probability of eacb case and a probable prognosis, and (3) presenting the case to the
commanding officer in an orderly and succinct manner.
The casualty may be transferred from the destroyer to the carrier by highline (stretcher or
bosun's chair), by helicopter, or by small boat. The patient wiU be considered either a stretcher
or nonstretcher case. A stretcher case cannot ride in the bosun's chair but must be transported
in the special Stokes stretcher equipped with flotation gear (Figure 17-4). Although stretcher
cases can be transported by helicopter, such is not recommended except in extreme
emergencies, unless ttie helicopter can actually land on the smaller vessel.
Best surgical practice dictates that every case of suspected appendicitis travel via stretcher
on the higUine. In actual practice, however, many such cases arrive without previous
consultation in the bosun's chair, and they seem to endure the trip just as well as in a stretcher
and are safer en route.
With the patient's arrival aboard the carrier and transfer to sickbay, the acquisition phase is
completed. Thereafter, casualties from all sources follow the protocol which is outlined below.
Triage
'When tiie patient, still oti the stretcher, has reached the emergency room, the medical
officer shoidfl quicMy make a working dia^osis, and preliminary measures of therapy ^ould be
started. If blood replacement appears indicated, a sample should be taken from the patient
immediately so that members of the "walking blood bank" may be identified from the records
and notified to report. It can take 45 minutes for blood to be drawn, typed, and cross-matched.
Only then can whole blood be administered to the casualty.
When severd casualties with severe injuries arrive together or in rapid succession, the
medical officer must make his working diagnosis rapidly in order to estabUsh priorities for care,
blood typing, surgery, and other services, in view of the limited resources available. X-rays and
clinical laboratory examinations must be ordered at this time according to priority. Obviously,
final decisions must be made by the Medical Officer in the case of multiple casuidties with
several medical officers attending them. It is he who must integrate the separate lists of
priorities and establish final ones.
E^ly Treatment
Air TransportabiUty
After triage is completed and the Medical Officer knows the number of casualties and flie
nature and extent of injuries and illness, he must decide which patients can receive definitive
17-16
Aeromedical Evacuation
treatment aboard and which must be evacuated to hospitals ashore. Of fQUrse, all patients
continue to receive emergency care.
Transfer of patients froiti an aircraft carrier at sea to shore facilities is nriost commonly made
using the C-1 or C-2A COD (Carrier Onboard Delivery) aircraft. The G-lf*w*feieh is illustrated in
Figure 17-5, has a cruise speed of 200 mph and a normal range of 700 nautical miles. Although
it is unpressurized, it has two distinct advantages: (1) It is assigned to the ship and therefore
under the ship's direct operational control, and (2) it is capable of a deck launch which is
sometimes desirable when the patient's condition will not tolerate the accelerative stresses
imposed by a catapult launch. The C-2A COD is pressurized, has a cruise speed close to
300 tiph, and possesses a normal raitgfe df 1^435 nautical ttifles. This aircraft is shown in
Figure 17-6. A litter kit is available for rapid conversion of the C-2A into a configuration
suitable for transport of six patients in Stokes litters. This conversion is illustrated in
Figure 17-7. VRC-50 and its detachments provide C-2A support for AIRPAC carriers, and
VR-24 is the supporting squadron for AIRLANT carriers.
(■• )
Figure 17-5. C-1 Trader aircraft used in transfer of patients
itom carrier to shore faciliti^ |5J;S. Navy photograph).
For emergency aeromedical evacuations involving shorter distances, helicopters may he
used. Figures 17-8 and 17-9 show the SH-3A Sea King and UH-2A Seasprite helicopters,
respectively, either of which might be used for this purpose.
17-17
Fi^re 17-6. C-2A Greyhound aircraft used in transfer of patients
from carrier to shore facilities (Courtesy of Grumman Corporation).
Figure 17-7. Interior of C-2A configured for transport of six patients in Stokes litters
(from U.S. Nuval Fli^pm^0«k Manual, 1968),
mm
Aeromedical Evacuation
Figure 17-8. Sea King h^Hc^pW^feii ' '
for emergency aeromedical evalucation (U.S. Navy photograph).
Figure 17-9. UH-2A Seaaprite helicopter used
for emergency aeromedical evacuation (U.S. Navy photograph).
If the Medical Officer feels that some patients may be evacuated by air, their treatment
from the very outset must reflect that possibility - that is, they must remain air-transportable,
and any therapeutic measures undertaken must not render their travel by air ittlpossibie. General
risks sustained by patients during air transport together with special management problems
17-19
U.S. Naval Flight Surgeon's Manual
engendered by patients with specific medical conditions have been discussed in a previous
section of this chapter. This early treatment phase represents, then, a finite, though variable in
duration, period of time between the point of patient acquisition and a final decision whether
or not to airHft the patient off the ship. It can best be spent resuscitating the patient with the
goal of achieving a condition stable enough to withstand the rigors of aeromedical evacuation
should such be the ultimate decision. Delay incurred in achieving a thoroughly resuscitated
patient in a stable condition is often preferable to a hasty and premature evacuation of a patient
whose deteriorated condition on arrival may Ittrther delay definitive therapy.
Evacuation Decision
The Medical Officer must take into account many fac^t0i$ when maMxi^ <^Mom regarding
the evacuation of patients. Some of these are:
1. diagnosis and prognosis of the patient
2. treatmentfaciH|ies-#^lfl{i|lii£^o^ ys» §mm a^ialable afloat
3. transportation available ashore
4. holding facilities available ashore
5. diplomatic and legal aspects
6. patient and crew safety in aeromedical evacuation.
Diagnosis and Prognosis of Patient A patient who is going to die without neurosurgical
intervention or one who wUl lose a limb without a vascular graft unless evacuated represents one
extreme. The other, is the patient with an undiagnosed ilbiess which might reflect only a
variation of normal ^r, on the oth» hand, might be fatd i|:.|f&f treated early. Of paramount
concern is the urgency for treatment, and an estimate itiMt he made of the effects of treatment
delay or deferral on the patient's prognosis.
Facilities Available Ashore. In order to determine whether there are adequate local hospitals
or whether transfer by air to a distant hospital is required, the Flight Surgeon should have a
comprehensive list of area hospitals, with the facilities and specialties available in each. It is
helpful to have a list of nearby airfields and a description of airfield -hospital transportation
arrangements, but these are seldom available. The Air Operations Officer can supply the names
of nearby airfields and a description of airfield facilities. The Port Directory usually has a short
description of local hospitals. A list of U.S. military hospitals and medical facilities is generally
available in foreign areas. Con^lar and embassy staffs can be of great assistance in d,etailing
local medical facilities and the diplomatic and administrajBTO'prbeedures required for admission
of patients.
17-20
Aeromedical Evacuation
Possibilities for transfer are shown in Figure 1710. The shore facility may be a hospital or it
may be an airfield from which further transportation to a hospital can be arranged. ' . >
Aiife^jift Carrier
I
(Maintain Air Transportability)
. ii Figure 17-10. Evacuation possibilities and modalities
(adapted from U.S. Navd Flight Surgeon's Manml, 1968).
When information about shore facilities has been received, the Medical Officer must decide
whether flies© fajrilities arp ^^^iciently better than those on the carrier to justify evacuation.
The carrier has a medium-sked liospital which is clean, dry, and air conditioned. Endemic
disease is not a problem. There is unlimited potable water and sanitation is excellent. Facilities
include a modern operating suite, intensive care unit, laboratory, x-ray, and physiotherapy
equipment. There are large quantities of sterile suppUes and an extensive choice of medications,
Four ipihysiciaiis (inehlding a trained surgeon), at least four dental officers (who give invaluable
assistance in emergencies), and a trained technical staff are available. Patients are secure from
attack, and there is an almost unUmited supply of whole blood. In many areas of the world,
such f aciUties are far better than anything ashore within thousands of miles.
17-21
U.S. Naval Flight Surgeon's Manual
Once the Medical Officer decides that the patient must be hospitalised ashore, n decision
must be made regarding the means of transportation.
Traasportation Modalities, If the hospital selected is within helicopter range of the ship, the
patient may be transferred directly to it. As an alternative, suitable surface transportation may
be arranged by transferring the patient to a smaller vessel which could take him to the nearest
port, with an ambulance completing the trip. A third possibility is that of having the patient
transferred via COD aircraft to an airfield from which surface transportation to the hospital
could be arranged. f
Should the area be so remote that the patient must be tranafeired tt& an mrfield by
helicopter or COD and further transferred to a MAC flight, there are several additional
problems. If there is an armed forces holding facility at the airfield, the patient can be
transferred ashore to that facility and maintained until the MAC flight arrives.
RoUUng FaetS^s. Holding facilities are those (such as a small i^perisary) which can provide
nursing care, intravenous therapy, and other emergency treatment, meals, shelter, hospital beds,
etc., for a period of one or two days for patients en route to a hospital for definitive care but
awaiting final airlift. If a facility adequate to handle the patient's problems is unavailable,
arrangements must be made to have the evacuation flight from the ship meet the MAC
aeromedieal evacuation flight and transfer the patient directly to the MAC aircipgft. Hiis type of
transfer: is difficult because it requires excellent communieations, good weather, and precise
timing. This combination is not always achievable. Weather will not hurt the patient, but it may
prevent the MAC aircraft or the COD aircraft from landing. Reliability of communications in
remote areas of the world differs widely. Any delay in the rendezvous may cause a wait of hours
in an aircraft, which is quite comfortable in the air but which becomes an oven or a freezer on
the ground.
A^flomtaie dnd Legal :Fai:tors. A potential ^ifficiiliy iv^ch tMU Be coffered the policy
of the nation in which the hospital, airfield, or any en route airfield is located. Su'tJh jpi^licy may
require diplomatic clearance and other administrative procedures which cannot be accomplished
within the time frame of the projected transfer. Again, United States Embassy and consular
staffs can provide invaluable assistance. ' •
Patient and Crew Safety in Aeromedical Evacuation. Safety of the crew of the helicopter or
COD aircraft is a fiirther consideration. It is far better to keep a questionable case on board ^m.
to subject the patient phis the aircraft crew to a flight m:ade unsafe by inclement weather,
enemy action, or mechanical unreliabihty of the aircraft. Aircrewmerabers will volunteer for
17-22
Aeromedical Evacuation
hazardous flights to attempt a lifesaving mission. The Fhght Surgeon must realize this when
deciding whether or not a case should be evacuated. He must consider the many facets of the
problem mentioned here plus the many others which will h&come apparent to him only on the
scene jand, at that time. Each facet exerts its own influence as a determinant in the
decision-making process.
Communications with MAC
Once the decision to evacuate has been made and approved, immediate attempts must be
made to communicate with MAC, if a MAC airlift is going to be required at some stage of the
evacuation process. Communications procedures are detailed in directives. General policy and
information are contained in OPNAVINST 4630.9 series (Air Force Regulations 164-1 series).
Specific information lor the area of concern is^ contained in directives of the locfd area
command. For example, in Ptetberai JEmsopie Coj^mander in Chief « VM., Savd Ferees,
Europe (CINCUSNAVEUR), has issued an instruction in the 6320.1 series which sets forth
procedures for aeromedical evacuation in that area. Such instructions normally include the
name of the unit which wUl perform the evacuation, the procedure for establishing
commnnication with the local Aeromedical Evacuation Control Officer, and other pertinent
i^lformation. ! ■
At the time of original contact with MAC, a precedence for movement of the patient VfXiSt
be established. There are three categories of precedence for pickup and movement:
1. Urgent — for an emergency case which must be moved immediately in order to save life
or limb or to prevent complication of a serious iUness. Immediate movement means that an
aircraft already in the air will be diverted or that an alert aircraft will be launched as a special
mission to pick ;tip the patfent and deliver him to his destination medical facffity. By^ dfiffiniHon,
tihien, psyehiatrie or termmal caiBS<w4ili a ve^ short life exptajtancy are not consid^ed iiTgent.
2. Priority — for patients requiring prompt medical care not available locally. Such patients
must be picked up within 24 hours and delivered with the least possible delay.
3. Routine — for patients who should be picked up within 72 hours and moved on routine
scheduled flights.
Generally speaking, U.S. military shore stations in most areas overseas have a scheduled
aeromedical evacuation flight which picks up patients routinely one or more times per week.
Such information, including the schedule of the entire system, is usually available through the
Aeromedical Evacuation Control Officer of the local area. He can also provide area supplements
to Air Force. iRegijlation 164-1 series (OPNAVINST 4630.9 series), which go into even greater
detaU on procedures.
17-23
U.S. NarsJ FHght Siii^oh'g Manual
When a reply is received from MAC, the decision to evacuate may have to be modified in the
light of facts contained in the reply. For example, if no aircraft is available or the weather will
not permit sending one, or if the MAC aeromedical evacuation flight cannot make satisfactory
e^knections, the Medical Officer may be forced to retain the patient and treat him aliddrd.
MAC must, of course, be notified of such decisions.
ionergency Treatment and the Walking Blood Bank '
While the Medical Officer is considering the question of aeromedical evacuation, the patient
is being given all necessary emergency treatment, subject to the limitations mentioned under air
tr ansportabiUty .
One of the most important lifiesaving measures is, bf eotlirsiB, whole blood tran^u^bn to
replied bted loss. Since needs for whole blood are infrequent, it wdUld be ui^eoncHM^Cdl to
maintain a blood bank of the ordinary type aboard ship. Ihstead, m^gt einrriesris havft a "Walking"
blood bank which is more suited to operational requirenf^'Gs,
Although the method of operation of the walking blood bank may vary from ship to ship,
the basic principles are the same. A log is kept by the Medical Officer listing a large nuttdy^r oF
personnel currently on board by name, rate, division, phone number, and blood type. When
blood is required, selected individuals having the required type of blood are contacted, and they
report to sickbay as soon as possible. Blood is donated by these individuals and collected in
blood transfusion bags while typing and cross-matching are performed. Soon after the blood
donation is completed, the unit of blood, typed and cross-matched, is available for transfusion.
Wha ipiwblems associated with operation of the wflktag blood bank are mainttuning eurrency
of the log, keeping an adequate supply of blood collection sets and bags on board, maintaining a
supply of fresh typing sera, and finding a sufficient supply of donors for rare blood types. For
example, there may be only three persons aboard with type AB Rh negative blood. If one such
person requires a transfusion, ordy two units of blood are potentially available.
When a decision is made to evacuate a patient, blood is sent with him, as wfll be lieited lat*;r,
' .1 • : . , ■ • ^ ■
Patient Preparation
When communications with MM^C Or with a hospital have been established and definite
plans for aeromedical evacuation can be made, preparations for the MAC flight must be
completed prior to departure from the ship, regardless of the initial transport modality.
17-24
Aeromedical Evacuation
Required administrative procedures, including patient classification, are defined in
OPNAVINST 4630.9 series, BUMEDINST 6320.1 series, BUMEDINST 4650.2 series, and
BU3VtEf)lNST 6700.2 series.
Required patient prepwatiQiiS include the following:
1. Prepare patient's identity card to include information as to sf ecial treatment required
en route, restrictions as to altitude and baggage, and any other special information. This card is
attached to the patient, as noted in BUMEDINST 4650.2 series. Patients must wear identifica-
tion tags, ' . . 1 n Mr
2. For patients outside of CONUS, prepare a five-day supply of special medications and
materials including drugs not normally carried by MAC medical attendants. All drugs should be
labeled with name and strength of drug, dosage, and directions for its administration.
3. Brief the patient regarding his aeromedical evacuation flight. The briefing should
include information on the manner in which the aeromedical evacuation system works; the
necessity for RON and regrouping of patients; specific or approximate routing with estimated
time en route; baggage limitation; the need for personal funds, appropriate uniform, and
U.S. Department of Agriculture and Customs inspections; availability of in-flight insurance; the
destination hospital, if fctiOWii, anclihow it was determinial; an4 oAer Jnf ormation that will
be helpful to the patient,
'" 4. Give preflight medicsttions. ' '
5. Apply clean dressings as near the time of departure as possible, particularly on
colostomies, draining wounds, burns, and pressure ulcers. Where frequent dressing changes are
required, a 24-hour supply should be provided.
6. Give intravenous fluids, when required, as close to the time of departure from the
carrier as possible. Intravenous catheters are kept open with slow drip of five percent dextrose
in water.
7. Apply indwelhng catheter in cajSies ijegpiinfing freqoen^t cathe^ In cases requiring
irrigation, provide a supply of irrigation solution to accompany the patient
8. Transfuse patients with a hematocrit less than 30 mg percent.
9. In a case of mandibular fracture, immobilize upper and lower jaws with tie elastic bands
rather than wire, and provide an emergency release mechanism. Each patient with immobilized
jaws hiis sj^sors attached to his^jerson, unless he is a Class lA or IB patient, or undef^gttiardi
1725
U.S. Naval Eli^t SurgecMi's Manual
10. Bivalve a cast which has been appliect within 24 hours of departure from the carrier.
11. Furnish masks to pulmonary tubeceulops cases unless it has been established that^if
infection is arrested or the patient is not infective. ^
t
12. Sedate neuropsychiatric cases Glass lA and IB, and deliver them to the aircraft onfa
Utt^ ia pa|amas.
13. Apply restraints to all Class lA patients and to any Class IB patients who may ^
combative, suicidal, or violent, and to any doubtful case. f
14. Brief the aeromedical evacuation medical attendants with respect to preflight
medications, characteristics of psychotic patients, particularly in regard to combative, assaulti^
or suicidal trends, and any special treatment or medication required by the patients.
15. Apply supports for those patients with extremity p^alym at palsy.
16. Provide food (including special diets) and food supplements not ordinarily carried oh
the type aeromedical evacuation flight contemplated.
In addition, htters must be prepared for expected weather conditions on the flight deck and
at the first transfer point (holding facility, hospital, or airfield) as necessary.
The patient's personal effects must be collected, inventoried, and packed; his records mu^
be brought up to date and prepared for transfer, and a summary of his present illness, at leaSt,
must accompany him in his Health Record, including laboratory results, x-rays, and any othdr
pertinent information.
The Fli^t Sui^eon must gatiier jnfottnation reijuired for patient prepja-ation and en route
support. He must be aware of the following factors:
1. Aircraft pressurization capability. Table 17-2 presents pressurization characteristics of
aircraft the FUght Surgeon is likely to encounter in aeromedical evacuation flights.
2. Fli^t altitude en roitte. When the presSurilBation capability ani planned fli^t altitude
are known, the Fhght Sui^on can recommend the maximum cabin altitude to which the
patient should be subjected.
3. Availability of emergency oxygen ecjuipment. If oxygen might 4W%ii«id b«l isnot
available aboard the aircraft, it can be furnished from ship's supplies.
4. Type of attendant required. It is usual for a trained and experienced hospital coipsman to
accompany the patient, but if the patient^ condition requires it, a Flight Sui^eon will attend him-r-
Aerom^dical Evacuation
Table 17-2
Cabin Pressurization Characteristics of Military Transport Aircraft
• Cargo-Transport
I C-1 . -
Not pressurized.
C-2
ft: Operational Setting: Cabin pressure altitude can be maintained at 4,000 feet up to a flight altitude of
22,000 feet. Above flight altitude of 22,000 feet, a pressure differential of 6.5 psi is maintained.
0-9
k Operational Setting: Cabin pressure attitude can be maintained at sea level to a flight altitude of
* 18,340 feet. Normal operational pressure differential is 7,46 psi. Maximum pressure differential is
8.0@ psi,
C-54
Not pressurized.
C-1 17
Not pressurized.
C-1 50
Operational Setting: Cabin pressure altitude can be maintained at 1,000 feet up to approximately
11,000 or 19,500 feet depending upon which modification of the aircraft is employed.
C-1 31
Operational Setting: Cabin pressure altitude can be maintained at sea level to a flight altitude of
approximately 7,500 feet. Operstijjpal maximiiitr pressure differential is 3.5 psi.
C-1 35
Operational Setting: Cabin pressure altitud« he riiaiWtiined at --^I.OOO feet (iSj (&i}'iQ a flight
altitude of approximately 22,50Q feet. Operational maxittium pressure differential is 8.6 psi.
C-141
Operational Setting: Cabin pressure altitude can be maintained at —1,000 feet (15,2 psi) to a flight
altitude of approximately 19,500 feet, A sea level, cabin pressure altitude can be maintained to a flight
altitude of approximately 21 jSpO feet. Maxiwum pressurit dil^ereotifl is i,g pSi.;
Patrol
P-3
Operational Setting: Cabin pressure altitude can be maintained at sea level to a flight altitude of
16,000 feet. Normal operational pressure differential is 6.70 f>si. Maximum pressure differential is
! 7.06 psi.
I : '^'^ ^ — — - <
(Modified froiri QreenwaldSi Mclver, 1967,prir»tBd by permisston of Aviation, Space, and Eni/ironmental Medicim) .
17-27
U.S. Naval Fli^t Sui>geoii's Manual
5. Expected flight duration, with ETD and ETA. The quantities of required medical
supphes, meals for in-flight feeding of patient, attendant and aircrew, consumables such as
oxygen, coffee, and drinking water, and arrangements for cabin lighting are all dependent on
this information.
6. Expected destination weather at ETA. Clothing, blankets, and other arrangements for
thermal comfort may be required en route and at destination.
7. Emergency egress from and emergency equipment on the aircraft. The attendant drtd the
patient need to have this information in the event of a forced landing either at sea or on land.
Arrangements must be made for emergency flotation either of the patient or of the entire
man-stretcher package.
8. En route stops planned, holding facilities availalle, and diplomatic procedures required.
Necessary visas, immunization certificates, and other necessary documents must be provided for
patient, attendant, and aircrew.
9. Location of attadiinent points for I.V. fluid bags, stretcher, and catheter drainage
receptacles. Such points may not be directly adjacent to :ftelocation selected for the streicherj
in the event of light failure, the attendant or Flight Surgeon must be able to locate them.
The Air Operations Officer can supply much of this inforiiiation. Hie remaflnder can be
derived both by flying routinely in the aircraft and by examining Ihe aircraft interior prior to
the evacuation flight.
Another necessary preparation is the collection and chilling of requisite amounts of whole
Mood to accompany the patient. The temperature of the blood may be maintained en fwnte by
placing it in plastic bags containing shaved ice. Whether oi not the blood is required during
flight, it may be useful after arrival at destination, since typing and cross-matching have Aeady
been performed.
IVanspoit from Sickbay and Aircraft Loading
Careless stretcher beareri can inflict injury to carefully prepared and stabilized patients on
the short trip through the passageway and up a ladder to the deck-edge elevator. The Flight
Surgeon should supervise the whole move, since his presence cabns both the patient and the
stretcher bearers. Tight strapping of the patient to the Utter will assist in preventing trauma
while loading through a narrow hatch or when the litter is in an unusual attitude. After loading,
the Flight Surgeon should check the provisions for emergency egress for both attendant and
patient as well ad assure himself that neither will be injured during launch and landing.
17-28
Aeromedical Evacuation
Emergency Patient Care En Route
In selected cases, the Flight Surgeon will accompany the patient at least to the first transfer
point in order to detect and treat ni|e^(E;sl^tttf Ifencies en rc^^t^ Weil tiii&illi^
it iiipiiferyj he shtiujW f pMwc witJi itlie patient until he is out of danger or has heen ttmifejl^
to other competentjpnedical personnel, t,
A patient who might go into shock en route, but who does not require a transfusion at the
time of departure, should have an indwelling venous catheter inserted prior to transfer. It should
be fctept 'o^fefe ivfffil.V. dextrose and water, administered through a blood transfusion I.V. set
which has been "pressurized" by taping all the points which m»|ht s§|m^ S^9|?)4I^^Xf
to be admilmtered under pressure.
Neither I.V. fluids nor blood run as freely kt Mftttt^e is 'it' ^ Ics^el, sfiiibe 1^6 ittotive ifofce
of atmospheric pressure decreases with ascent. Therefore, if Mood must be given rapidly,
additional pressure must be applied^ usu#y by using a rubber bulb. If the fli^t is in an
operational aircraft, the rear compartment hghting is usually poor, there is inadequate space,
and most normal medical monitoring is less than satisfactory. The wise Flight Surgeon will
prepare for the worst prior to leaving the ship, because there is no place to turn at 10,000 feet
at night, two hours from destination, with a patient wtio suddenly goes into profound shock or
begins massive hemorrhaging.
As noted previously, typed and cross-matched blood should be carried with the patient. If
not required in flight, it may be useful later at the hospital or aboard the MAC flight.
The pflot should be kept informed of the patient's condition 80 Gm$^MX^^i^^it
to past Itie Flight Surgeon. In some cases he can find a less turbulent altitude. In others,
he can decrease altitude or increase airspeed. He can radio ahead for ambulances, surgical teams,
unusual supplies, or other ground assistance, so that it v/ill be wailing when the aircraft lands.
He may be able to alter the flight plan and land at a nearby airfield with faster access to a
hospital than that available^* the original destination.
Holding Facilitiee at Transfer Point
Holding facilities, as the term is used here, do not indude casualty staging activities
established by MAG in their worldwide aeromedical evacuation system. Such, MAC activities are
generally well run and more than adequate. The Navy problemr is in obtaining similar services
from much more modest installations wherever in the world the casualty occurs. The Fhght
Surgeon must improvise to obtain adequate care for his patient, if Ms exaiftiiiation of'thy^
available faciUties shows them t^& Ife faadfeflift^. '
17-29
U.S. Naval Flight Surgeon's Manual
The adequacy of the holding facilities has previously been mentioned as an important factor
in deciding whether to attempt a direct transfer from the ship's COD or helicopter to the MAC
aerommm &vmmon flight 'at th^^ ai»fieia &t «6'«frifasfer the patient to the holding facihty.
•IwfoiBfiiadffl Wftflabte t& th#-PI|^t Surgeon aboard ship about the holding facility is frequently
incomplete and outdated. In such cases, it is far wiser to plaii a direct teansfei-.
Patient, Records, and Property Transfer
The intratheater (initial) transport phase ends when the patient has been delivered to the
hospital or to the MAC aeromedical evacuation flight, and the necessary records have been
transferred, and the ship's property signed for. BUMEDINST 6700.2 series covers the property
exchange and accounting, and the Flight Surgeon and/or medical attend W should familiarize
himself with these procedures prior to leaving the carrier. I ' I
Mertheater Tra^8|^rt Phase
This final transport phase ii entttely under ^e operations' control pf Mc. If lie patieiit
has been properly resuscitated, and if the plmnimg wid exemtioji of segment of
travel have been successful, then minimum probltems should be encounfJei^d in tjie inter^eater
transport phase. ' '
References ' ,1 <
Department of Defense. Air transportation eligibility (DOD Regulation 4515.13R). 6 P^ttttey 1975.
Department of the Navy, Bureau of Medicine and Surgery. Documentation accompanying patients aboard
taflitcity t;6iithon carrieiS (BUMEDINST 4650.2 series).
Department of the Navy, Bureau of Medicine and Surg^. Medical regiilatbi^ to atfd'witHin fiie cbiitinental
United States (BUMEDINST 6320.1 series).
Department of the Navy, Bureau of Medicine and Surgery. Property exchange accounting in evacuation of
patients (BUMEDINST 6700.2 series). .
Department of the Navy, Office of the Chief of Naval Operations, jter transportation eligibility (OPNAVINST
4630.25 series).
Department of the Navy, Office of the Chief of Naval Operations. Worldwide aeromedical evacuation
(OPNAVINST 4630.9 series). ■ ■ . •
Funsch, H.D., & Hankins, J.W. Jet age evacuation of Vietnam casnaltieB. Resident Fkyshkit, Sepie!mhet 1966,
88-90.
Green wald, A J., & Mclver, R.G. Cabin pressurization characteristicB of USAF and commercial transport
aircraft. Aerospace Medicine , 1 967, 58, 834-837.
SecFBtiflrjr ©f the Navy. Medical services uniformed services heaMi benefits program (SECNA VINST 6320.8) .
U.S. Naval Flight Surgeon's Manual. Prepared by BioTechnology, Inc., under Contract Nonr-46 13(00), Chief of
Naval Operations and Bureau of Medicine and Suigery. Washington, D.C., 1968.
17-30
Aeromedical Evacuation
Bibliography
FAA issues information notice concerning air ambulance transportation of patients. Aerospace Medicine , 1974,
45, 688^89.
Guilford, F.R., & Soboroff, BJ. Air evacuation historical review. Journal of Aviation Medicine, 1947, 18,
606-616.
Johnson, A., Jr. Treatise on aeromedical evacuation: I. Administration and some medical considerations.
II. Some surgical comiderations. Aviation, Space, and Environmental Medicine 1977, 48, 546-554.
Johnson, A., Jr., Cooper, J.T., & EUegood, F.E. Five-year study of emergency aeromedical evacuation in the
United States. Aviation, Space, and Environmental Medicine, 1976, 47, 662-666.
Randel, H.W. (Ed.). Aerospace Medicine (2nd ed.). Baltimore: Williams & Wilkins Co., 1971.
White, M.S., Chubb, R.M., Rossing, R.G., & Murphy, J.E. Results of early aeromedical evacuation of Vietnam
casualties. Aerospace Medicine, 1971, 42, 780-784.
17-31
c
C )
r
i
n
CHAPTER 18
MEDICATION AND FLIGHT
Introduction
Objectives
Effects of Drugs
Present Drug Usage
Specific Druga
Alcohol
Drugs in Non-Pilot Populations
Summary
Referenoes
Bibliography
( \
liiedicatian caotl kfll. For this reason, it is of paramount importance for the Flight Surgeon to
be aware of any drugs an aviator under his care may be taking. This may be di;tfi<s|^| Ji9 ^
because of the ready availability of sinus medications, cold preparations, sleeping piUs, Junfl p,
va^ty of other "over-the-counter" medicines at most drugstores, some grocery markets, and
also at the Navy Exchange. With the increasing medical sophistication of the general pubUe
through radio and television advertising and through articles in popular magazines, there is a
definite possibility of self -diagnosis and self -prescription. ' ' " '
Authority for recoiftmemiitotg.ithfe fcetwdillg of siviatm iteteing niedications coniet Jsgin
se¥er|4 sources. The Manual of the Medical Department (NAVMED 117) recommends that
persons requiring therapeutics be found not fit for flying. Further, Chapter 15, Article 70 orders
that "All aviation personnel admitted to the sicklist or hospitalized shall be suspended from all
duty involving flying." Paragraph 710 b (9) of the NATOPS manual (OPNAVINST 3710.7H)
imposes two restrictions regarding medication and flying. First, the Flight Surgeon should
indicate thft necessary flight Uniltittl^lls'tJltt 1jll prescriptions for flight personnel. Second, aviators
are prohibited from tilting tHedfeati^tts within 12 hours of flying unless prescribed Ad
approved by a Fli^t Siirgedn.
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U.S. Naval Flight Surgeon's Manual
If only Flight Surgeons treated flying personnel, there would be fewer problems. However,
it is important to remember that flying personnel may be treated by any physician, whether
civilian or mflitary, and whether in the Flight Surgeon's office, the emergency room, or in an
outpatient chnic. This situation poses two problems. Frequently non-Flight Surgeon phymcians
are unaware of the hazards associated with taking medications while flying. Thus, they mtU fail
to warn the aviator of the dangers, fail to ground him, and fail to label the prescriptions with
appropriate warnings. A second and related hazard is that all the medication may not be used up
with the initial illness, but may be saved and used later for another ilbiess. By then the aidator
may have forgotten the need to restrict his flying. To help prevent this, it may be helpftil to flag
an aviator's medical record with a brightly colored instruction sheet warning non-FB^t
Surgeons to ground the aviator until he can be seen by a FU^t Surgeon.
The proper course is to ground flying persoimel until their illness and their need for
medication have passed. Any physician may recommend grounding of flying peraormel. Only a
Flight Surgeon can recommend clearance to fly. This authority is in recognition of the Flight
Surgeon's special concern for flying safety and his special training toward that end. It imposes
upon him a corresponding special responsibihty which should not be undertaken li^tly.
Objectives
The basic objective of a FUght Surgeon is safety of flight. By his wise decisions, a Fhght
Surgeon is directly responsible for saving both lives and costly aircraft. This is not only
preventive medicine, but also cost-effective industrial safety being practiced at a very personal,
physician-patient relationship level.
Idedly, preventive medicine should be practiced so that flying personnel are kept healthy
and have no need for medication. However, when drugs do become necessary, they should be
selected so as to produce, if possible, a fast, permanent cure, do no harm, and have the fewest
possible side effects. The benefits of this approach for the patient are to keep him comfortable
during the healing process, to restore him to health, and to preserve and prolong his career. The
henefits for the Navy derive from the cost savings effected hy preventing the loss of expensive
aircraft, by prolonging the careers of valuable, expensively trained, flying personnel, a«d by
keeping effesstfve and on-the-joh key personnel directly responAle for accomplishing the Navy
mission.
Effects of Dni^
Berhapa the most important factor to he considered when deciding whether to ground an
aviator for taking jnedication is not the medication itself, but rather the disease for which the
medication was prescribed. Normally, any illness significant enough to bring flying personnel Lo
18-2
Medication and Flight
the Flight Surgeon or to prompt the Flight Surgeon to prescribe drugs may be sufficient in and
of itself to warrant consideration of grounding the aviator. If either the disease or the drug has
effects or side effects which would impdr Ijie physical, mental, or emotional functiomng of the
individual, then grounding should be considered.
In deciding whether to ground an aviator taking medication, it is important to analyze
the effects of the drug, and then relate these effects to iJie misfflon and to fke individual's
role Stt flie fllMon. For instance, gastroenteritis in a radar operator aboard a large patrol
aircraft could be handled in a much different Way from the same disease in the pilot of a
single-seat, fighter aircraft. In the latter instance the disease alone might ground the pilot.
Where the effects of the drug compromise an individual's ability to perform effectively and
safely, and where they decrease his ability to withstand the stresses of flight or of a survival
situation, grounding of the aviator should be considered. On the other hand, where prior
testing has shown the drug to accomplish its purpose and to produce no adverse side effects,
the Flight Surgeon may decide to prescribe the drug for use in flight when it is necessitty for
accomplishmfilit of a mWon. Such an example might be the prescribing of antimotion
sickness drugs for student pilots, accompanied by an instructor, for their first few f hghts or
for their first acrobatic flights.
In analyzing whether to allow an aviator to use chnigs in fli^t, all effects of the drugs
should be considered. Many drugs have more than one effect -some are desirable and
intended, and others are unwanted side effects. The latter are further subdivided into
predictable physiologic responses, unpredictable physiologic responses, and idiosyncratic
reactions. Examples of drugs which might demonstrate these side effects are atropine and
other anticholinergics. The intended physiologic response m.^t be suppression df acid
production or ^trotntesiansffl motihty. A predlcti&le, unwantejl Mde effect might be
pupillary dilation and decreased accomodation. An unpredictable, unwanted, physiologic side
effect might be the degree of an individual's heart rate response to the G-forces of flight. An
idiosyncratic reaction might be a rash or precipitation of glaucoma. Other drugs may be
analyzed similarly.
Basic to the analysis of a drug's applicability in flying personnel is the requirement that the
physician know all the effects and side effects of the drug (even if this requires going back to
the books to find them). Information on the side effects of drugs is available from many
sources. One which is useful is "Guide to Drug Hazards in Aviation Medicine" written by W.C.
Cutting, M.D., for the Federal Aviation Administration, It is AvsMMe through the Super-
intendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. The Fli^t
Surgeon must fliett imalyze those actions as they relate to aviation safety. The following listing
gives some of the factors to be considered.
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U.S. Naval Flight Surgeon's Manual
Literference With Normal Bodily Functions
1. Vision — Does the medicine cause pupillary dilation or photophobia? Does it decrease
ifieo'ftiodffldft Md bati^ Mttfrihg of vision of deei-ea^Sea vigual acuity, etc.?
2. Cerebration - Does the medicine produce drowauiess, coirfusion, illusions, hallucina-
tions, disorientation, psychosis, etc.?
3. Blood pjtfsgure, pulse rate, vascular tone, and myoeaFdial contractiHtf — Does tiie
medicine affect any of these factors in such a way as to cause hypotension? significant
hypertension? arrhythmias? alter the body's normal reaction to stress?
4. Temperature control — Does the drug affect the central fltermai reguktory centers or
the peripheral mechanisms (sweating, vasodilation, etc.) involved in temperature control? How
will this affect an aviator if he is sitting in a cockpit which has a "greenhouse effect"? or if he is
down at sea in cold water?
5. Oxygenation — Does the drug affect A« fate Or depth of respiration? Does it alter the
chemical ability of the blood to become oxygenated or to release oxygen to the tissues? Will the
drug cause anemia, etc.?
6. Comfort — Will the drug cause distracting, uncomfortable side effects such as dry
tt«iuth?'itehing? fflushhag, etc*?
7. Gastrointestinal function — Does the drug cause nausea? stomach cramps? diarrhea?
constipation, etc.? Will it interfere with motihty and cause trapped-gas problems?
8. Vestibular System — Does the drug cause vertigo? or decrease the individual's threshold
for motion sickness? Will it in any way increase his susceptibihty to disorientation?
9. Homeostasis — Does the drug cause chemical derangement of tiie body? Does it alter
the body's capacity to respond to changes in fluid intake, etc.?
10. Musculoskeletal — Does the drug Umit the motion of any extremity or of the spine?
Doeftlt cafiise unwanted, itt^lUhtaiy niovementif
Ability to Withstand Stress
1. Hemorrhage — Does the drug cause bleeding? Will it adversely affect the body's abUity to
cojje with bleeding if injuries are sustained?
2. <M€iFCes — WiU the drug decrease an aviitor's ability to cope with G-forces during
aircraft maneuvering or ejection?
18-4
Me#eati6n and ¥lt^t
O
3. Heat- Will the drug predispose to heat stroke Wlliir^sil its eflset be? on an aviator
waiting at the end of the runway for takeoff in a cockpit with a "greenhouse" effect? • ■
4. Dehydration - Does the drug cause diuresis? decrease fluid intake? increase inse^fihle
fluid loss or sweating?
5. Survival situation — WiU the drug decrease an aviator's chances of survival in case of a
crash or ejection? Does it sensitize the myocardium to arrhythymias with exposure to cold
water? Will he be able to survive without injury in a survival situation if he does not take the
medicine?
6. Change in batditfetric pressure - Does the drug cause mucosal swelling which might
block the sinus ostia or the eustachian tubes? Does it delay gas transport in the intestines and
lead to trapped-gas problems, etc.?
7. Hypoxia - Does Ihe drug tend to.«^ufe hypoxiat Does it change %m body's response to
hypoxia? Does it obscure the pilot's ability to recognize hyjjofia? Does the action of Ihe drug
change in the presence of hypoxia, etc.?
1 J i ; ••• . ; - ; 'i .
Risk of Incapacitation
'' ^ 1. Sudden - What are the chances that the disease will cause sudden incapacitation? If the
disease doesn't, could the drug suddenly render an aviator incapable of performing his duties?
Could it cause unconsciousness? severe pain? tetany? vertigo? decreased visjjid aCMiiy, ^e,? ^y
drug or disease which could cause interference wiih an aviator's ability to function effectively
shotlid bfiB considered a eSlElse for grounding.
2. Insidious - Insidious incapacitation is sonleiines^uA' harder to identify or to ''j^mM^
than is sudden incapacitation and is thus much more dangerous. The pilot who gets>^eii%ojtoi
faints due to prthoftatie hypotension as a side effect of a drug will probably ground himself.
However, the same pilot taking a sleeping pill because of domestic problems may not even
recognize the decrement in his performance which persists for hours the next day, even after the
obvious soporific drug action has worn off . . „ ,
Insididus incapacitation is an even greater problem when a drug will be used over a period of
several days, weeks, or even longer. Problems such as potassium depletion from some diuretics
may not manifest themselves until the patient has been on the drug for a long period of time.
Even then, an additional stress, such as dehydration, may be necessary to make the condition
manifest. The time interval from an av^^o^s starting a dfUg uiittt he c^uld be considered safe to
fly, must be long enou^for any cumulative effects to manifest themselves. It must also be long
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U.S. Naval Fli^t Surgeon's Manual
enough for an aviator to experience all the side effects of the drug and to learn to recognize
those side fjfects. ... • i , < .'■.< />■
Modification of Drug Action Due to Flying
The Flight Surgeon must consider all the stresses imposed on an aviator by flying and how
these stresses will interact with the effects and side effects of the drug. As an example, hypoxia
is dangerous enough by itself. A borderline case of hypoxia, that might not have resulted in
fatality, might be converted into a sudden catastrophe if an aviator is taking systemic
decongestants or using nasal Bpmj for a cold. Adrenergic drugs and sympathomimetiis sensitize
the myocardium to the effects of hypoxia and can cause dangerous, suddenly incapacitating
cardiac arrhythymias. Another example is the lack of alertness which can result from the
additive effects of fatigue and drowsiness from antihistamines. Many amilar examples will he
apparent to the concerned Flight Surgeon.
' ' Present Drug Usage
At present there is oidy one drug, hydrochlorothiazide, aulhori^ed f or use witibout a waiver
in flying persoimeL This drug, subject to certain restrictions, may be used to control
hypertension. First, it must be demonstrated that this drug used as the sole medicinal titerapy
will effectively control the disease. Second, an airman must have been on the drug for a
sufficient length of time for the drug to demonstrate all its side effects, and an aviator must not
show any of these side effects. At the Naval Aerospace Medical Institute, an observation period
of four weeks is used.
Certain other drugs may be considered for waiver for long-term usage on an individual basis.
Among these are low doses of tetracycUne for acne, antimalarials for prophylaxis of malaria,
mifeosurics for treatment of hypemricemia, thyroid replaeement therapy, and antitub^rculai^
Each individual tO be considered for waiiyer fbr a long-term course of medication raiist be
thoroughly evaluated. Ih general, if an aviator is to be grounded for over 30 days because of
dru^ (or other reasons), an SF 88 Should be completed and forwardgdi to B0MED
[OPNAVINST 3710. 7H 1082 a.] with an appropriate recommendation.
... i< . Specific Drugs
Antibiotics
Antibiotics which can be prescribed for use by an outpatient are multiple, and the chance
that aviators will need them is always present. In addition to individual specific side effects,
some general side effects or reactions deserve comment.
18-6
Medication and Fli^t
1. Allergic reactions to antibiotics, especially penicillin, are not infrequent. Immediate,
sudden incapacitation may occur with anaphylaxis, angioneurotic edema, or asthma. Less
dramatic Btit ^tiU'^otentiafly dangerous skin rashes and urticaria occur witii regularity. '
2. Bone marrow toxicity develops with some antibiotics, notably chloramphenicol. The
resulting anemia or decreased resistance to infection poses a risk for aviation duties since it may
be present for some time before being diagnosed.
3. Ototoxicity occurs primarily with the polypeptide group of antibiotics which are
ordinarily reserved for more severe infections. Nevertheless, aviators will receive them
occasionally. Either hearing loss or disequilibrium may result and disable an aviator.
4. Other posdble side effects |tre iQulli]^le *^d reguire consideration.
Ncm-narvotic Analgedcs
Two general types of analgesics are in common usage, the saUcylates and the aniline
derivatives. They are commonly available under names such as aspirin, APC's, Bromo-Seltzer,
Alka-Seltzer, Tylenol, etc. Due to their extremely common use, there is a tendency to forget
that they do have adveree e^cts. "Araqng "these are gastritis, tinnitus^ loss of hearing, and
ttieititiMoglobinemia.
Sulfonamides
Sulfonamides are in frequent use for treatment of urinary tract infections. Among their
adverse effects are methemoglobinemia, decreased depth perception, accentuation of phorias,
t|gjl|g^j» vproitii^, dizziness, dermatitis, agranulocytosis, and hepatitis.
Topical Medications
In general, most topical preparations are safe to use with flying. However, sbme oifttffii*lfei
that are petroleum baie# *i^tay oxidise rapidly in the 100 pierfcirft oxygen enviroiunefit ttf'l^if
aviator's in#k liad probahly sK^IjM
' Alc oh ol , ,
Alcohol is # ^im^ but, due to its wide saeial use, there is a tendency to forget that and
regard it only as a beverage. Aviators are specifically prohibited from flying within twelve hours
of last consuming alcohol [OPNAVINST 3710.7H paragraph 710 b. 5(a)] . The acute toxic
effects of central nervous system depression, uncoordination, and altered judgement are well
known, but other effects of alcohol are sometimes forgotten. These include diuresis, gastritis.
18-7
U.S, Naval Fli^t Surgeon's Manual
myopathies (and especially the direct effect on heart enzymes producing cardiomyopathy),
hepatic damage, peripheral njeuropathiei, and long-term central nervous system complications
<itelerium tremens, cerebral atrophy, psychoses). Alcohol affects multiple body systems
adyersely.
For more ex tensive coverage, see Chapter 19, Alcohol Abuse.
Drugs in Non-Pilot Populations
Crewm embers
Most of the preceeding comments apply equally well to non-pilot crewmembers and to
pilots. In some cases, different standards may be used to judge fitness to fly, and it is up to the
individual Flight Surgeon to exercise h^ best judgement in making exceptions.
MedeviH^ and Passengers
Since passengers on routine flints and patients on Mectevac flints are not primarily
responsible for the safety of the flight or the completion of the mission, differ^t Standards
apply in deciding whether to allow them to fly when using drugs. Basically, the consideration is
whether or not it is safe to fly when taking a particular medication. Again, the basic disease for
which the drug is taken should be considered first. Then the effects of the drug should be
assessed in relation to the particulais of that flight (type aircraft, altitude, oxygen equipment
aboird, etc.).
A word is in order about certain drugs. Sedation and p4n reHef are frequently necessary on
xMedevae fligfits. Although most Medevac flights are in pressurized aircraft with oxygen
equipment aboard, the potential for respiratory depression and resultant hypoxia should be
considered in patients for whom narcotics, barbiturates, or chloral hydrate are prescribed. The
possibility of loss of pressurization or other emergengf faapot be di^pafeied. Chloral hydrate, in
addition, ha? the potential for cardiac depression, ian^ehyde is probably the safest sedative for
in-flight usr>. hnl iias the disadvantage of a very prominent odor which might aggravate tive
tendency to nmlion sickness of other persons in the airplane. The newer drugs, flurazepam and
diazepauK a(*jjrar to cause less respiratory depression at effective doses than do the older
hypnotics and tranquilizers. Belladonna alkfdoids and dtiier parasympathetic depressants are in
frequent use for peptic ulcer disease. However, theymay contribute to traplied-gas problems.
Summary . <.
When considering whether an aviator should or should not fly when taking drugs, the
general medical condition of the patient should always be the first and overriding concern of the
18-8
Medication and Fli^t
Flight Surgeon. Then the effects and side effects of the drug should be considered as they
interrelate with the requirements and stresses of flying.
If a pilot must fly, then the Flight Surgeon should discuss, with both the aviator and his
commanding officer, the interference with the accomplishment of the mission which ruay be
attributable to the disease and the drug. He must provide them with the factual basis to decide
whether the mission is more important than the safety of the pilot or the plane, and whether
the pilot can accomplish the mission. It is the Flight Surgeon's duty to make flight more
effective and safe. He must determine an aviator*s fitness to fly. The eommandng officer must
determine the need to fly.
Referrals
Cutting, W.C. Guide to drag hazards in aviation medicine. Federal Aviation Administration, Aviation Medical
Service. Washington, D.C.: U.S. Government Printing Office, 1962.
Department of the Navy. Mcmual of the medical department, U.S. Navy (NAVMED117), Washington, D.C.: U.S.
Government Printing Office.
Departmmt of the Navy. NATOPS Gmerd ^ht and opmrating inttmctions (OPNAV Instruction 3710.7
Series). Washington, D.C.: U.S. Government Printing Office.
Bibliography
Goodman, L.S,, & GUman, A. (Ed£.). The pharmacological basis of therapeutics (5th ed.). New York:
MacMiQan, 1975.
Physician's desk reference, OradcJl, NJ.: Medical Economics Co., 1977.
18-9
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CHAPTER 19
ALCOHOL ABUSE
Introduction
Definition of Alcoholism
Diagnosis and Detoxificatidti '
The Rehabilitation Pro^^
Summary
Appendix 19- A- Laboratory Tests Helpful in the Diagnosis of Alcoholism
Introduction
The problem of alcohol abuse and alcoholism among members of the aviatiQti community is
as old as aviation itself. Althou^ isolated reports have pointed to alcoliol idiuge as a cause of
aviation accidents m general aviation, ;^e problem of alcohol ^fHfejilM or alcoholism in naval
aviation was never admitted to exist, openly discussed, or scientifically shidied. This was due to
two factors:
1. The stigma of alcohoHsm as a moral weakness (incompatible with the hegyf. drin|^ii^
manliness image of the "scarf in the wind" aviator)
2. The traditional handling of alcohol problems through administrative and punitive
channels which always led to ruinad eareers and often to loss of retirement pay.
In point of fact, however, heavy drinking and frequent drinking have become a part of our
way of life both in the United States as a civilization, as well as in naval aviation as a gubculture.
From a psyeholo^cal Standpoiaf, we use it to control almost any iMft in ttui* eBfli61ions.^e''also
use it to assuage psychic pain, loneliness, uneasiness, to celebrate, and to mourn. In terms of its
intended chemical effect, we tend to use alcohol as a stimulant, antidepressant, sedative,
analgesic, tranquihzer, aphrodisiac, and soporific.
Socially we use it when we feel good, when we feel bad, as a pick-me-up, ta^0itm dowti, as
an eye-opener, aiid as a nightcap. At cocktail parties^ We use it to say "heUo,** i6 g^tfa St^Cfe
unwind, to break the ice, and finally, as "one for the road," At dinner parties, we use it as an
appetizer, as a main beverage (beer or wine), as an after-dinner drink, and as "more of the same"
during late-evening socializing. Before we drive home, we have "one for the road" toward the
nightcap before bedtime. All of these are followed in the morning by a Bloody Mary or "some
hair of the dog that bit us."
19-1
U^S. Naval Flight Surgeon's Manual
Executives discuss business while having cocktails. The salesman buys another round when
he lands the contract. If his sales pitch falls through and the customers leave, he is apt to buy a
double to control his frustration.
In sports, we drink at the clubhouse, at the golf shack, on the beach, during the hunt, and at
the races. We drink cold beer at baseball games because it is hot in the bleachers and Irish coffee
at football games because it is cold in those bleachers. Winners drink to celebrate; losers to dim
the agony of defeat.
We drink when we hear good news, when we get bad news, when we go off to war, to
celebrate peace, to commemorate a birth, or mourn a death. We drink at birthdays, reunions,
Christmas, Halloween, and the New Year, Drinking goes with courting ("Candy is dandy but
Uquor is quicker," said Ogden Nash), with engagements, marriages, anniversaries, and,
nowadays, with divorces.
If you now feel happy th^ you are in the Navy instead of out Ihere with all those
hard-drinking civihans ~ read on.
lii naval aviation, we drink at happy hours, after a good flight, after a bad flight, and after a
near mid-air collision (to Calm our nerves). To celebrate our first solo flight, we traditionally
present our instructor with a bottle of his favorite liquor, and, if we successfully bail out of a
crippled airplane, we express our thanks to the lifesaving parachute rigger with a bottle of his
preferred spirits. We drink when we get our wings, when we get promoted (wetting-down party),
when we get passed over (to alleviate our depression), at formal dining-ins, change-of-command
ceremonies, ChiiE^* mitiatiotis, and at "beef and burgundy night." At bihhday balls, we drink
our door prize if we have the lucky ticket.
When a diver inspects the huU of a ship, we give him medicinal brandy, and we prescribe the
same treatment for exposure to the elements if a man falls overboard and is fished out of the
Caribbean on a hot day in July. i
A night carrier landing sometimes rates medicinal brandy dispensed by the well-meaning
Flight Surgeon. We "hail and farewell" frequently, and the first Uquid that wets the bow of a
newborn ship at its christening is champagne. We drink from ei^tment to retirement and from
teenhpod to old age. ,
If heavy drinking leads to alcohol-related problems and to alcoholism, then a society that
dl^p^ like ours, or a Navy , that drinks like ours, will certainly realize its fullest potential
C
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19-2
Akohol Abuse
for creating alcoholics. The potential danger to the aviation cojnmunity conies from several
sources:
1. Acute intoxication (or even minimal "social" use shortly befort: or during flight
operations or before performing equipment maintenance work) becausfc of the effect of
alcohol on judgement and neuroMu^ullur iioordihation
2. Hangover with synlptoms of headache, fatigue, nausea, irritabilily. «i;d: impaired
jUflgement and neuromuscular coordination
3. Chronic use of alcohol over a period of months or years leading to alcoholism as a fatal
illness
4. EfBte«ts "bf lepeafeid aletthol abuse br Edcoholfsm 6n the faitfilf'. Mends, i&id
acquaintances of the afflicted
5. Administrative difficulties including discipUnary problems, mediccd problems,
absenteeism, and material damage.
The potential dangers frequency become a realty because the following aspects of the
problem are either not generally known or, if suspedfeeli, Wfe ^t>red by medical as well as line
officers in the aviation community:
1, j^lcohol is a drug belonging to the sedative, hypnotic group. It acts as a depressant and
an anesthetic with subsequent hangover and a rebound period of irritability or agitation
in anybody who drinks it (social drinker and chronic alcoholic alike). Forty percent of
"heavy drinkers" eventually become alcoholics.
2. Alcoholism is a disease which affects not only those who have it, but it also has a
pronounced deteriorating pyschological, social, economic, and physiological effect on
tiie family and friends of the alcoholic.
Of the many dctinitions given, the common denominator is that alcoholism exists in a
person when alcohol use and damage to the person's life l>y alcohol coexist. The World Health
Organization definition is as follows: "AlcohoUcs are those excessive drinkers whose
dependence upon alcohol has reached such a degree that it results in noticeable mental
disturbance or in an interference with their bodily and mental health, their interpersonal
relations, their smooth social and economic functioning, or tJiose who ^ow the prodtr6:nilal i^gtts
of such developmiBhts.
In the Navy alcohoUsm prevention program, we have used the foUowii^ workable definition
as an indicator that the person in question has developed dcohfthstO ar is f lap t<p djev^Bfiingiit
and needs a careftil examination to determine the extent of his alcohol problem. The Navy
19-3
U.S. Naval Ilight Surgeon's Manual
dvjlinition says that an alcoholic is anybody whose drinking has begun to seriously interfere with
one or more of the following aspects of his life: family life, sodal life, legal ftFe, financial life,
physical heldtlii mental health, ^ilitual life, and occupational Mfe.
Diagnosis and Detoxificatioii
Medical History ^'
Unlike the history -taking in most othef diseasfe enMlifeS,'6re Kiftori iMdrtiiMon in
alcoholism often has to be obtained from more than one source, and the exammer has to put or
fit the pieces of the puzzle together in order to visualize clearly the extent of the disease process
in the patient. Sometimes the history, as given by the patient himself, is adequate, but usually
this is not the case because denial is a primary symptom of alcoholism. In obtaining the history,
the Flight Surgeon should keep in mind the aforementioned list of the eight areas of a person's
functioning. The interview sKoidd be directed at establishing some kind of relatiohE^P ^between
alcohol use and the deterioration of one or more areas of the patient's life.
The history can often be obtained from the patient's wife, his friends, and his superiors, all
of whom know his daily living habits and his work performance. When the patient is seen in the
emergency room, supplemental information can often be obtained from those who brought him
to the emergency room, including cab dfivers, policemen, or Mends. In addition to determining
extent of destruction which has taken .place in the patient's life, the Flight Surgeon ^onld
try to establish whether or not the patient has alcohol tolerance and whether or not he has in
the past or is presently experiencing withdrawal symptoms. Questions about tolerance are,
again, often better addressed to the family and friends or superiors of the patient. If the patient
is far advanced into alcoholism, or if he is trying to deny his illness, he will often minimize the
amount of drinking he actually does. '
Ute ni^t Surgeon is in an ideal position to make the diagnosis of alcoholism because he
lot only knows the patient's family, friends, and superiors from his daily interaction with his
squadron, but he also has access to the patient's health record and service record. Both of these
can be very useful supplements to the history-taking process.
The health record wfll indicate the frequency and nature of dck calls, hospitalization, and
injuries. The health record should be analyzed by haying a tiiree-year calendar handy so that one
cm see time and frequency patterns, such as frequency in calk and injury during holidays and
on weekends, including Monday mornings. At the same time, an analysis of the alcoholic's
deterioration is ofterv reflected in sick call or hospitalization of family members foif injury,
de^essii^e reactions, family discbifd, etc.
194
Alcohol Abuse
O
The patient's service record can also supply further information about the alcoholic's
deterioration by shedding light on such things as letters of indebtedness, letters of reprimand,
humanitarian franefeis, and having 1» be evacuated from overseas.
Physical Findii^
Depending on the degree of deterioration, the patient will show involvement in one or
practically all organ systems. Like syphilis and tuberculosis in the past, alpohoUsin has become
today's greatest imitator of all other disease processes.
The vital signs will usually reveal a rapid pulse, sometimes with extra beats, and
patieilt ttiiiy* tow adilitional symptoms trf witMrawrf'tacfi'W ^kin or
vital
hypertdifiiten. Thd
pei
A general examination may show varying degrees of jaundice with spider angioma, multiple
recent bruises or healed injuries for which there are no good explanations, a palpable liver, and a
protuberant abdomen with ascites.
The extremities may also reveal multiple bruises, recent injuries, or superficial infections.
TTie neurologic ex^ination may reveal tremor, peripheral neuropathy, or hypo- or hyper-
reflexia with decrease in muscle strength.
The mental status examination will usually be characterized by gross denial, by either
clearly inappropriate or manipulative behavior, and by obsequious or antisocial, aggressive
confrontation of the therapist in order to avoid being exaiained for alcoholism.
In terms of his sensorium, the patient may be anywhere from comatose to obtunded,
seemingly normal to euphoric, depressed, hallucinating, delusional, or in frank delerium
tremens.
Hie laboratory tests whidh are most helpful in making liie diagnosis are ^ntaiiied-ini&e<]ji0
of National Council on Alcoholism (IfCA) criteria in AppMdix A.
Where a question remains in regard to diagnosis, it is often helpful to refer the patient, for
evaluation by the trained and experienced counsellors at a rehabilitation facility.
The Detoxification Procedure '
For the patient who has tolerance and withdrawal symptoms, detoxificatiori in a medical
ward win be necessary bftfbre h'e can be cbnsi'dered for rehabilitation. B is important that the
physkian and the entire treatment tedfrt continue to look Upon detoxification not as a metftodP
19-5
U.S. Naval flight Surgeon's Manual
of treatment, hut as a means of re ferral into treatment. Probably the most important ingredient
in the detoxification procedure is the attitude of the nursing personnel and others who come in
contact with the patient.
The following orders can be used as a model for detoxification:
1. Vital signs every four hours, or more often as necessary
2. Bed rest with bathroom privileges
3. Five-point restraints as necessary
4t Lifted roam at ni^t
5. Librium, 50 mg by mouth or intramuscularly every two hours for withdrawal
symptoms or agitation, as necessary in the nurse's judgement. Total Libriun][ should be
under 500 mg per 24 hours. It is often sufficient to order Librium 25 mg q.i.d. on the
first day, 20 mg q.i.d. on the second day, 10 mg q.i.d. on the third day, and to
discontinue it on the fourth day.
6. Magnesium sulfate, 50 percent solution, 2 cc intramuscularly twice daily for 48 hours
7. Thiamine, 100 mg intramuscularly on admission
8. Thiamine, 50 mg by mouth q.i.d.
9. Nonavitamines, one by mouth every day
10. Chloral hydrate, 500 mg by mouth at bedtime. This may be repeated once and is
discontinued after 24 hours. T
11. Mylanta, 30 cc by mouth every 4 hours PRN
12. Tylenol, 10 grains by mouth every 4 hours PRN
13. CBC, urinalysis, VDRL, SMA 12, electrolytes, chest X-ray, and blood alcohol level
14. Electrocardiogram if over 35 years of age or as necessary.
Psychiatric hiterview
Since alcohol use and alcoholism is a loaded subject in our society, ihe examiner must be
aware of his own attitudes in this regard. He must have worked through his own socio cultural
tendency to consider alcoholism as a moral problem, and he must have learned to use the NCA
diagnostic criteria as indicators of illness, rather than to compare the patient's drinking history
with his own drinking style. Since denial is the number one mental mechanism used by an
sdeohoUc, and since most patients will react with avoidance or hostility when their denial is
coi|d|foittcid head-on, the examiner mast trmn hijt»s©lf tQ listen to the style and <|uality of
responds , W^C^h the patient makes. A peifeBti who has no problem with alcohol use will answer
ihe questions on that subject in a matter-of-fact way. The person who has some early, private
19-6
Alcohol Abuse
concerns about his alcohol intake, however, or the person who is already suffering from chronic
alcoholism, will direct his whole style of responses with one goal in mind: persuading the
examiner that there is "no problem." As the examiner assesses the various areas of the patient's
personalifry "fianctioning, the patient's reepoMsies will sound superficially negative but subtly
quaUfyiilg, iuch questions if® "Do you dririk very much?'' or "Does yoBt drinMMg iirteriai^ #lh
your family life?" will be answered by superfiefaUy negative but deliberately vague, meaningless
responses such as "not as a rule; no more than everybody else; not recently; not really; nothing
worth mentioning; probably not; I wouldn't say so; practically never," etc.
The examiner must leam to titrate the pafient^ hostility e^efuUy by first paying attention
to the manner in which the patient was relatiJig to hiffi at thebfegiflttiJKg of the Mter^^ew. A-tol^
line is estabhshed by rtoting such items as the tone of voice with which the patient spoke, the
degree of friendliness or emotional distance with which he was addressing the examiner, the
amount of trust he seemed to place in the examiner and medical people in general, the degree of
litigiousness or propensity for paranoid hostility, etc. Most of these will markedly change when
the examinee sbtfts his questioning from a review of sf^it^ttis or from gastrointestiiial problems
specifically to aleohol me or possible jficoho&mv It it feiportant to establish ^©lii^ i?a|qpi|it
with the patient "SO thitt 'he wiUretwrnfoSra^^ '
Confrontation and Intervention
Alcoholics practically never ask for help purely and simply because of their own realization
that they have a problem and that something now needs to be done. A close look at all of the
circumstances surrounding a patient's coming to attention and a thorough interview will usually
reveal the reason for the patient's seeking help. Viewed from this standpoint, it can be said that
all intervention in aicoholan hfppens because the patient has come to a crisis in his life
situation. The basic intent of early intervention and rehabilitation is to bring about a crisis
earlier in the Ufe of the alcoholic so that intervention can be followed by rehabilitation at a time
when the patient stiU has all, or most, of his psychosocial resources available for use in the
rehabilitation process.
GonfrontatiDn should be a joint effort involving significant people such as the Flight
Surgeon, the patient's commanding officer, the patient's wife, a teenage daughter or son, his
friends, and/or his chaplain. Confrontation is best done in the Flight Surgeon's office after he
has gathered all of the information and individually persuaded several of the aforementioned
people to involve themselves. The Flight Surgeon must not select people who have a current or
long-standing vendetta with the potential patient, siicti as a separated or divOfcIf^ mfe or aai
angry stepson. He must also not select people wbo have an unshiiikahleljond of loyalty with the
potential patient, such as a crewmember or flying buddy whose life the patient once saved or his
19-7
U.S. Naval Fli^t Surgeon's Manuitl
favorite drinking companion who might also need to deny "the problem." Each person in the
confrontation setting should have previously written down a number of items with which he is
wilhng to confront the patient. The items should clearly reHeat a sitaa^cgi; io. iMr|iich €le
patient's drinking caused him or others harm, expense, embarrassment, etc. This^ould involve
everyday, real life situations. The patient must hear these presentations from beginning to end.
The theme of the confrontation should be that all parties concerned arc there because they love
the patient, because they are worried for him, because they want to see him get help, because
they are convinced that he has an alcohol problem. It must also be stated that they are, in the
case of family, prepared to leave the patient if he does not get help, or, in the case of the
commfflFid, that they are ptepared to take proper administrative or disciplinary action if hs does
not get help. The entire confrontation has to be orchestrated by the Flight Surgeon, who has
before him the patient's health records, service record, and outpatient record with available
laboratory data, etc.
It is usually beat for the confrontation to take plaee after the patient has become involved in
detoxification, or, if this is not necessary, then after the patient has had a drinking bout and is
atUl emotionally upset and depressed because of guilt in connection with his alcoholic bjefeavior.
Referral to the nearest treatment facility needs to be arranged by the Flight Surgeon, much as
he would make arrangements for treatment of tuberculosis, diabetes, or any other illness. At
this time, the patient must be told that alcoholism is a treatable disease and, if applicable, that
he vwU return to fuB flying status Sabaequrait to treatment if he responds properly.
Hie Rehabilitation Frogram
Organization
Alcohol rehabiUtation facUities are organized at several levels, progressing from the Alcohol
Rehabilitation Dry docks jdioard most stations and many large ships to Alcohol RehabiUtation
Units occupying wards in m^^ naval hospital, to Alcohol Rehabilitation Centers, and finally,
to the Alcohol Rehabilitation Service at NRMC Long Beach and the Alcohol Rehabilitation
Program at NRMC Portsmouth. As one moves from the Drydocks to the highest echelon of
facilities, there is an important trade-off: Increasing staffing resources and technical sophistica-
tion are substituted for proximity to both the supportive miUeu which might assist in recovery
and the stresses^ and problems which were used to rationalize drinking in the first place. The
qjecific needs of each alcoholic must be coiisida-ed so that he can be referred to the type of
program which will be best for him. The Flight Surgeon ^ould become familiar with the
facilities available to him as soon as possible; there wiU be an opportunity for him to involve
himself in the local program, perhaps making presentations to tiie patients or consulting with
the staff.
19-8
AlcohoE Abuse
Treatment
Unlike other services, the treatment approaches in all naval alcoholism treatment facilities
are uniform. Patients will usually be in a restricted status for the first two weeks of treatment;
they receive a complete physical examination and a battery of psychological evaluations upon
admission. After detosificatidni if 1Mb h neeessiary, the patieni mil not fee treatediinth any
medications other than antftbuse aftd murltivii^imi ifee iti an Inpiiient iai^li^ wilh
otlier recovering alcoholics of all ranfcs and hotti s^fiS.
The main features of the six -week rehabilitation program are group therapy, under the
leadership of recovered alcoholic Navy active duty counselors, and thorough indoctrination into
the principles of IfHe feflowiii|^%f Aleoholics Attonym^^^^^ (AA). The day is^fflteii'iwth group
therapy sessions, educational movies on alcohol and alcoholisto, didaefie lectures, psydhodrfflua,
family treatment, couples' therapy, phyaifesl fltness, and nightly attendahce at AlcohoHcs
Anoaymmis. i^eetinp in the civilian eommiipit^.
The treatment philosophy is that the patient is entering treatment because his life has
become unmanageable, because he has lost his abiUty to use alcohol without causing harm to
himself and others. Every effort during the six-week rehabilitation is aimed $t hm0XigMin^ ill
toueh with feeUngB which he has not been aware of, usually for years, making hira somewhat
n^ll^;, aware of the mental defenses which he characteristically uses. The intent is to restore him
to a sober, happy person who functions without alcohol and other mind-altering chemicals, so
that he can again effectively perform his role in the naval community.
Follow-Up and Maoagemmt of ittel^eovered AlcohoUe
C>#r 95 percent of= all pJ^ents treated in naval alcoholic rehabilitation facMtiei aie
retrffhed'tO Uie dtft^ Sta^tt where they were assigned prior ^ entering te^tm^t. In tN
case of flying petsaiia<^, there may or may not be a statement concerning the patient's
suitability for return to flying status in the narrative summary. The actual disposition, in
terms of when and how the patient returns to flying status, will become the responsibility
of the local Flight Surgeon. He is the one who sees the patient Back in the squadron
environment and" %!ED! " have daily opportunity to observe the patient, his supmors, lus
family, attd otheifs. The proeedures for retuming a etiswmember to flyMg i stttus are
outlined in BUMED Instruction 5300.4A of 19 April 1977.
Unless the Flight Surgeon has had some prior indoctrination in an alcohol rehabilita-
tion facility as a participant observer, he may never have had. the experience of dealing
with a recovwii^ s4coh#Ct Mf^| sounitty recovering alcoholics ^mider themselves iii; no
way different from other people except that they no longer drink alcohol. Some of the
19-9
V.S. Naval flight Suigedji's Manual
qualities which are iniiicative of the patient with a good working progrsim of rmmMW' W^
the following:
1. He no longer drinks alcohol or takes mind-altering drugs of any kind unless they are
prescribed for an emergency, an elective surgical procedure, etc. ^ ■■.<
2. He comfortably accepts ttite fact thai Imlm jflcdhblism. Jfe'iio'long^ wiAdeys M^ieAfer
Ihgi etiology is biochemical, genetic, ©feij -iBid he no longer hopes ijiat someonie will
invent a magic piU so that he can drirdc again socially.
3. He is no longer very concerned with personal anonymity. As a matter of fact, he makes
sure that his commanding officer and his squadron mates know that he is an alcoholic.
.4. He is actively involved in helping other alcohohcs find sobriety, and he regularly attends
, lAlcoholics Anonymous meetings. If he is ii^ family or group pj^chQtheiapy , ttfis 18 as. mi
adjunct to Alcohohcs Anonymous.
5, His sesnse of tiumpr ha^ re1wip[ie4,^nd,tie q^,nq^. ^'^p^t critici^p:j \srhen }^e,is,T|¥x;9ng.
It is important that the Flight Surgeon convey to the patient that he understands the
way of life of the recovering alcoholic. This can be done by showing the patient that he is
comfortable around non-drinking friends, that he respects the right not to drink, and that he
expects the same degree of commitment and the same level of performance? ^folll 'lfae
non-alcohErliC 'M^hi Mm "fymi 'thi^' mcJcSvering alcolt##v' fhfc l)irt^%^Vf# tfe©' Wi^fr Sbtpoil
to actually mMl#" fte pKfiress of tite tfeiJttveffiii 'ffifedhflte' :i^W Peimfelftbef 'is -to
occasionally attend an AA meeting with him and his family. For the first year, the Flight
Surgeon should have at least monthly, regularly scheduled, personal interview sessions with
the patient. These interviews should take place in the Flight Surgeon's office much as any
other interview or examination. If there is any suspicion, or if the Flight Surgeon obtains any
information which euggests that the patient may haye rdapsefd to drinking again, the patient
^ul£ be ^undedi unttt- the , FJ^t Slii^eon, is ifii^n <;rf, tiae .aqto^ cij3iu?QiriSttiqes.^I£'11iere
has indeed been a relapse, the pa^eMiWlft' lieecl (to ^tsi evaluated and a determination made as
to whether or not he should be returned for another course of rehabilitation. According to
the Bureau of Naval Personnel Directives at the present time, the Navy Alcohphsm
Prevention Program will give a patient two complete courses of rehabilitation provided that
there kft *biieni S<att4 reaionabfe; improy#Went;,ar 4^?©:. # function^ between the first
rehabiUtation and the first relapse. Only undp? exti^tWS^sly . Wjnjsu^^ will a thwd
course be made possible. Separation from. tb# iesr^Cp beipUSB Qf, 4fifM i^^fe
Chaptex 16, Disposition of Problem Cases,
Prognosis
Well over half of all participants in Navy rehabilitation programs experience a "recovery"
and are maintaining sobriety through the fed' of iSreiJf first yeai^^ltffe discharge: -fhfe iff an
aveiage flgiite; the outlook is less f iaVorable for the immaturb youn|'^ltfsoM f or whoni alcohol
Alcohol Abuse
may be just one of many drugs he abuses and for whom alcohol abuse is just one more means of
expressing his dissatisfaction with his situation. The prognosis is vastly more favorable for the
older, more mature, profesedonally motivated aviator, N.F.O,, and medical officer. Relapse
among the latter groups is unuaial; most such people return to suceeSsjftil careers. Likelihood of
promotioti, selection fot eonimtod, and ai^gwueiat to positions of responsibility are, by
established policy, unaffected by one's identity as a recovered alcoholic. An office at BuPers
(Code 64) has been set up to guard against discriiiiination.
Summary
Excessive drinking as a sign of manliness is probably as old in aviation as aviation itself.
Alcoholism and alcohol-related problems were ignored and treated administratively and
punitively until 1971 when the Naval Alcoholism Prevention Program came into being. Since
then, alcoholism is treated as a chronic, progressive, and relapsing disease which affects members
of the aviation cotiimunitj jmt as it affeete other people. It ft essenliai that the Flight Surgeon
leain to think of alcohol as a sedative, hypnotic drug and that he be familiar with the potential
hazards which excessive use of this drug presents to the aviation compunity.
The history and physical examinations done in connection with alcoholism present a unique
problem in medicine in that flie patient^ primary mental mechanism, denial, usually makes him
an unreliable historian, and, therefore, other sources, such as friends, fiottily, superiors, and
health tecords, need to be utibzed. The diagnosis should be based on the diagnostic criteria
promulgated by the National Council on Alcoholism. It is important to begin to see
detoxification not as treatment, but as a means of referring the patient for proper
treatment - rehabilitation. The examiner should be alerted to the possibility of alcoholism
whenever a patient goes overboard in his efforts to convince the Flight Surgeon that there could
not possibly be such a problem. Alcoholics only get into treatment as a result of life crisis which
csanbe broa^t about earlier in the progression of the disease by confrontation and intervention.
GonfrontatiQH needs to be orchestrated by the Flight Surgeon and should involve significant
other persons such as family members, senior officers, friends, the chaplain, etc. The aim of the
confrontation is to assure the patient that significant people are concerned about him and that
they insist on his going for treatment. At risk is the possibility of family members lea\ ing him
and superiors instituting administrative or disciplinary actions.
Rehabilitation means restoring the patient to a way of life in which he can function without
the use of alcohol or other mind-altering drugs in his capacity as a flight crewmember and as a
member of his family and society. Follow-up care means not only checking on the patient's
abstinence but, more importantiy , bein^ aware of and, ide#y, even being a part of his on-going
emotional growth. This can be accomplished by being briefly involved in his Alcoholics
19-11
U.S. Naval Fli^t Surgeon's Manual
Anonymous way of recovery, at times, and by holding monthly interviews in the Flight Surgeon's
office with the patient and, occasionally, with family members and senior officers.
The Flight Surgeon has a very important role to play in helping to Aspe the dWrifcipgj|tyles
of his flight crew. A letter from the Surgeon General of the United States Navy, Vice Admiral
W.P. Arentzen, had this to say about the drinking practices of the Navy:
The time has come to focus on prevention, as well as rehabilita-
tion...Our seafaring tradition includes rituals with heavy drinking,
based on tenacious myths that heavy drinking signifies vigor and
promotes good fellowship. Such folklore stemming from the days of
the galleons has no place in modern medicine in a modern Navy. It is
incumbent on us in the Medical Department to dispel these myths, not
only by our utterances, but more importantly by our leadership
actions and by our example.
Take a close look at irrational drinking customs at your command,
take remedial action, and msist that your staff members act*
exemplarily and responsibly in their consumption of alcohol, or avail
themselves of rehabilitation.
It is my desire that the Medical Department take a leading role in
the curtailment of irresponsible drinking in the Navy.
19-12
Alc ohol Abuse
APPENDIX 19-A
LABORATORY TESTS HELPFUL IN THE DIAGNOSIS OF ALCOHOLISM
Di^nostic
Level
Msfor — Direct
Blood alcohol level at any time of more than 300 mg/100 ml 1
Level of more than 100 mg/100 mt in routine examination 1
Major — indirect
Serum osmolality (reflects blood alcohol levels): every 22.4 increase over 200 mosm/l iter
ref I ects 50 mg/1 00 m I alcohol 2
Minor — Indirect
Results of alcohol ingestion:
Hypoglycemia 3
Hypochloremic alkalosis 3
Low magnesium level 2
Lactic acid elevation 3
Transient uric acid elevation 3
Potassium depletion 3
Indications of liver abnormality:
SGPT elevation 2
SGOT elevation 3
BSP elevatfon 2
Bilirubin elevation 2
Urinary urobilinogen elevation 2
Serum A/G ratio reversal 2
Blood and blood dotting:
Anemia: hypochromic, normocytic, macrocytic, hemolytic with stomatocytosis, low folic
acid 3
Clotting disorders: prothrombin elevation, thrombocytopenia 3
ECG abnormalities:
Cardiac arrhythmias; tachycardia; T-waves dimpled, cloven, or spinous; atrial fibrillation;
ventricular premature contractions; abnormal P-waves 2
EEG abnormalities:
Decreased or increased REM sleep, d^ending on phase 3
Loss of delta sleep 3
Other reported findings:
Decreased immune response 3
Decreased response to Synacthen test 3
Chromosomal damage from alcoholism 3
(National Council on Alcoholism).
19-13
r
I
o
u
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o
CHAPTER 20
FATIGUE
Introduction
Fatigue in MiUtary Operations
MetsusfBsiettt of Opwational Fatigue
Dji8C»|Bign
Role of ;tJie Flight Surgeon
References
I i ■ ■ '
Introduction
Military operations are characterized by sustained effort, physical exertion, and prolonged
vigilance - all of which lead to fatigue. That fatigue is a by-product of military schedules Mtt
demands cannot be questioned. There are, however, many questions and unresolved fesues
concerning the maikner in which fatigttie dietSltjps, itt iiii|JbW«fii6e M the military, and the best
way to manage it. The Flight Surgeon is in a key position, although perh%S an unenviable one,
to assist operating personnel in dealing with the problem of fatigue.
Literally milhons of dollars have been spent in studying fatigue, yet its essential nature
remains more unknown than known. RoM McFarland, founder and for many years the director
of the Harvard Fatigue Laboratory, noted in a 1971 review that, "Definitions of them^re of
fatigue are almost as numerous as the articles that have been written about it, since each
depends largely upon the interest or technical background of the author." The varying
interpretations of fatigue, according to McFarland, are due to the fact that the word has no
specific scientific meaning. It does not represent a distinct cHnical entity. Rather, it refers to ^
group of phenomena associated with impairment or loss of efficiency and skiU, and the
development of anxiety, frustration, or boredom.
Fatigue problems described in the technical literature seem to fall in three broad classes. The
first is chronic fatigue, largely psychogenic in origin, which is produced by boredom and/or
progressive anxiety and is cumulative in effect. This internally generated type of impairment
reqitiHeS- m^ediM or psychiatric treatjnent and is not necessarily dUeviated by rest. The mMM
ty|»e'<Sf fatigue is referred to as aciitfe, mA i| ptteduced by brief but very tiring work output.
Acute fatigue operates principally on the muscles, rather than being a systemic condition,
20-1
U.S. Naval Fii^t Surgeon's Manual
resulting in a temporary condition which is relieved hy rest. The third type of fatigue, and the
one of most consequence for the Flight Surgeon, is referred to as task-induced fatigue or
operational fatigue. This fatigue is produced by long hours of work or work in a taxing
environmentr Participation in laiKtary nrisaions, particularly if they are carried out over a
number of days, presents a perfect example of ^ of fatigue. Here the loss of efficiency is
attributable both to physiological and to psycholo^cal factors. Loss of sleep frequently is one
component of the forces acting to produce operational fatigue.
A Fhght Surgeon must be sensitive to the problem of operational fatigiie and the variables
which are instrumental in producing this condition. Although operational fatigue is difficult to
measure with precision, there is no doubt that it is real. Extended mihtary operations,
loi^kg'dui-atioii sp$ce missions, and other activities which are hi^y goal-oriented and Which fest
over many days, can result in this type of fatigue. Navy combat operations provide a classic
example. When a carrier is on the Une, aviation personnel are asked for maximum effort
day-after-day. Squadron schedules may call for pilots to fly as many as three missions a day,
with numerous briefings and debriefings in between. Launches scheduled for 0300 are not
infrequent. Last-minute changes m operating plans add to the hectic quality of the period.
Aviation combat brings together three ingredients which are beUeved to be major
contributors to operational fatigue. These are the shortening and disruption of normal sleep
patterns, changes in nutrition brought about by eating quick foods at odd hours, and the unique
Stress imposed by the Ufe and death nature of combat itself.
Fatigue in Military Operations
A first Step in studying fatigue in military operations is to examine the evidence describing
the exteist to wKch fati^e reduces individual eJfectivieness or increases accident potential
Unfortunate, evidence frbih field studies and laboratory iavestigations often is contradictory
and does not provide a clear-cut picture of the nature of operational fatigue. There are,
however, some findings of interest and some points which can be made.
Accident Investigations
A good example of aviation missions in which fatigue-inducing factors should be prominent
is in antisubmarine warfare (ASW) exercises (U.S. Naval Aerospace Physiologist's Manual,
19f 2)- During a typical A|^ exercise, aircrewmen may log as many as 150 hours in a 40-day
period. Flights durmg such exercises can last as long as 12 to 16 hours. Sleep is»disturbed or
sharply curtailed. In the P-3 aircraft, for example, as many as 16 individuals can be on a single
flight with only two bunks available for use during periods of reduced activity. Further,
20-2
Fatigue
individuals often are called upon to perform at peak levels at a time of day when performance,
as reflected in Mological rhythms, can be expected to be poorest.
A survey of major iwijdidents to P-3 aircraft over a seven-year period -was made by Shannon
and Lane (1971). Between calendar years 1962 and 1969, there were 16 major P-3 accidents,
excluding those from hostile action. Accident characteristics examined included time of day,
phase of flight, mission, geographical area, and causal and contributory factors involved. The
most frequently n«9itM>ned an^e centi&iating imt&t vrm ^iiUmm fatigue. In eight of the
eleven accidents Which involved personafcl failtoifii, fatigue was listed as contributing to the
errors made by pflots and crewmen. The authors felt that in some situations, f iatigue may have
led to the precipitation of the emergency; in others, fatigued personnel were unable to react
appropriately to emergency conditions created by factors beyond their control.
A review of comments eotteendiig oi^! of ftfe P-3 accidents shows a tjrpical form of
operational fatigue and the way in wbaich it Interacite wMfi otiier e^^eats. In ttris accident, die
aircraft flew into the water during low-altitude ASW locaUzation, with eight fataHties and four
major injuries. Cpninci^Js froni the Acddent Investigation Report include:
The Plane Commander had ilown a VP/SS training^i^t
night prior to the accident during the same hours (0000-0600)
and with the same exercise submarine. This previous flight was
the first flight he had flown in eleven days. He and his crew had
been id JlOttg Koflg for amm days . , .
Upon returning from this previous ASW ffli^t (at 0600), the
crew was not scheduled for another flight until 0800 the
following day. They went to bed under this assumption. A
schedule change was made to allow another crew to have the
daylight period for a more difficult qualification exercise. This
change moved this crew up to another midnight takeoff. There
were some bitter remarks made by several of the crew's officers
concerning the change, particularly when, in their opinion, they
did not need sub time since they had all the required quahfica-
tions and had proven their proficiency just the night before.
However, when they reported for the flight, they appeared rested
and in good spirits.
The operational tempo of flying for Ihis period had been
close to the hmit possible for continuous operation. This
particular crew averaged over 100 hours of flight time per month
for the last three months. During this period a rate of operation,
had been established that could be accepted, as it was in support
of their shipmates captured by the Norfli Koreans. It could have
20-3
U.S. Naval Flight Surgeon's Manual
been maintained in time of national emergency or even for other
operational ^e flying requu-ed in thi^ afea of the Pacific.
However, in addition to the heavy tempo of operational flying,
there have been ASW training periods available. In order to peak
up the crdw% ASW readiness, all submarine services were
accepted. As these services were flown in addition to all i.
operational commitments, the stage was set for discontent. It is a
known fact that crews resent training flights when they are
r, al^ilir woii^^M«ut of evety^
rii ■ . weeks without a true day off. Thus, a possible poor
, j ^ ^ attitude on the part of some or all of jthe crewTOQpifeere may h^^^
been established.
Playback of the Ground Control Tape reveals a sleepy or
gro^ Bifleclion in &e copilot's voice. At Hus time the PPG of
_ the aircraft being reheved noted an apparent lack of usual vitality
j ^,^ in the radio transmissions by the copilot. The bland radio
communication was not normal for the copilot and unusual to
the extent that other aircraft's ^tit G^ikmtM dttit. The
evident lack of energy reflected in the copilot's UHF o^mmimt&6a'
tion reflects either an apathetic attitude or some indication of
incstpadtkil&tti
The aircraft descended from a stated 650 feet into the water
in an apparent 1-G maneuver. How Hie iteraft descended
650 feet without the pilot, copilot, or engineer noting the
descent or radar altimeter red warning light is the primary
qmi&tioh. It toist be assittiaed ithat^mther they were all incapacita-
tsd or had their atteMon dB^tted db^wh@x®.
Aviator fatigue has been found in hehcopter operations as well as with fixed-wing aircraft.
In a review of 120 rotary -wing accidents occurring during normal peace-time operations in
Europe in NATO forces (Perry, 1974), it was found that some 15 percent appear to have fatigue
as a contributory cause, although in many instances sufficient specific information was lacking
to make a clear-cutloii^i , j ■, ,<
Field Studies
It is always difficult in accident investigations to pnipomt 0SM^ with peeision. This is
particularly true when one is trying to assess tke role of such elusive agents as fatigue. For this
reason, there have been a number of field studies in which an attempt w^js m|^e to control the
magnitude of fatigue and to measure resulting changes in proficiency.
A very relevant study, for present purposes, of the landing performance of Navy pilots
flying jet drcraft was conducted by Brictson (1974). Two sq[uadrons of naval aviators flying the
204
Fatigue
F-4J fighter aircraft were used as subjects, with two squadrons of A-7 pilots serving as controls
in the sense of providing comparative data for a different aircraft type. Each carrier landing was
evaluated through a Lan&g Performance Scofe (LPS), a measure based on an equal interval
scale of landing qusB^ ihat represents an LSO consensus of the relative numerical vatoe of eatii
possible landing outcome. Pi'evious studies have shown this to be a sensitive and valid criterion
of pilot carrier landing performance.
In the Bricfcon study, pilot workload, presumed to hear some relation to operational
fatigue, was estabhshed at three levels. Zero cumulative workload consisted of landings made
after a prolonged nonflying period. Moderate workload was defined by 11 consecutive days of
flying missions over nonhostile territory. High cumulative workload level consisted of 22 days
of consecutive flying over hostile terrain with a high degree of danger. Results found for
F-4 pilots for the three levels of cumulative workload are presented in Figure 20-1. TTie change
in landing performance for daylight operations is not significant and fluctuates around the mean
day performance score obtained during the entire cruise for these pilots. The increase in night
landing performance from moderate to high cumulative workload is statistically significant and
can be interpreted as a genuine increase in landing proficiency. These results, then, for these
levels of cumulative workload, show no decrease in performance which mi^t be attributed to
operational fatigue. In fact, at least under thf jaight flying conditions, there is an increase in
^ - proficiency. Twenty-two days of consecutive combat flying, at least for these two
' F4 squadrons, did not produce any operational fatigue condition which affected landing
performance.
In another study atlemptiilg to identify tiie point at which operational fatigue becomes
important, O'Donnell, Bollinger, and Hartman (1974) studied the effects of an extended
mission length on the performance of an airborne command and control team. In this test, three
EC135 aircraft teams, each with 17 team members, participated in a four-day continuous alert
in which one aircraft was airborne at all times. Crew performance was eyahiated through
questionnaires completed by team members^ systematic observation of the performance of team
members by ibe eaqierimenter, and a ^neral content analysis of briefing materials obtained at
the completion of each flight.
On examining the performance measures from llie above test, the authors conclude that
"there was absolutely no indication that the teams' performance would suffer as a result of this
regime and, equally important, there was no indication that any performance deficit was
beginning to show up. No trend was observed in the data relating to efficiency, mistakes, quaUty
of coordination, style of performing, or capabihty to respond to an emerjgency. This lack of
trend implies fbat one can reasonably hypothesize that the teams could have continued the
same schedule for a longer period of time." It is apparent that a four-day emergency alert does
not tax skilled crews to the point where operational fatigue becomes of consequence.
20-5
U.S. Naval Plight Surgeon's Manual
BASELINE SCORES
5.2
Landing
Performance
Score (LPS)
I
5.0
4.8-
4.6
4.4-
4.2L
Zero Moderate
LEVEL OF CUMULATrVE WORKLOAD
High
Ouise
X Day
• Night
Figure 20-1. F4 day and ni^t landing performance scores for three levels
of cumulative workload (adapted from Brictson, 1974).
Fieet
X Day
t Night
Summary of Fatigue-Study Findings
The identification and measurement of operational fatigue and its effects are not easy to
accomplish. Retrospective examinations of aircraft accidents indicate it may be an important
cause of accidents which occur following periods of extended operations. Subjective reports of
fatigue, as obtained in a host of studies, indicate that such fatigue does exist and does build as
the work program continues, even though some measure of interim i®st is provided. Field tests,
however, generally fail to show any deterioration in measured performance which might be
attributed to fatigue. This is true for studies of continuous work lasting for as long as 48 hours
and for extended periods of combat flight operationi lasting for as long as 22 consecutive days.
Results of these studies clearly show that young, highly motivated, healthy individuals can
perform for quite long periods of time before operational fatigue results in a measurable
disturbance of performance. Obviously, there muSt eome a time when performance suffers, but
this time can be postponed for a longer time than one might think.
20-6
Fatigue
Measurement of Operational Fatigue
There has been considerable interest in recent years in the development of a measurement
system which will tell the extent to which an individual is suffering. from fatigue and/or stress
and, in consequence, represents an increased risk for operattotifil duty. At a recent conference
cOttceraing biomedical research and development requirements in the Navy, heW in Charleston,
South Carolina (Office of Naval Research, 1973), Captein Robert E. Mitchell, MC, USN, stated
that, "There should be something in the way of a biochemical technique which could be carried
out aboard a carrier or at a Naval Air Station and which would teU us in a matter of minutes
where the man stands."
A Flight Surgeon fe rfesponsible for monitoring the physical fitness of an aviator to perform
his flight assignments on a day-to-day basis. This is a difficult thing to do, particularly with the
limited observation time and other information available to the Flight Surgeon concerning an
individual aviator. If the FUght Surgeon had an appropriate diagnostic measurement system, he
would not have to rely on cUniCfll judgement alone, but could use objective measraes to tell
when fatigue has reached a point at which performance impairment is imminent. Hopeftilly, this
information would be available well in advance of any actual deterioration of performance. The
obvious value of such a measurement system has caused a number of investigators to study the
components of fatigue and to seek quantifiable relationships between some measurable index
and the fatigue state. Unfortunately, the development of a rehable and valid measurement
system for operational fatigue remains more a goal than a reality.
The following sections describe briefly some of the lines of inquiry being pursued and the
general success of recent research efforts. A more detailed picture of the state-of-the-aJct i« iJie
measurement and prediction of operational fatigue is available in a 1975 review by West and
Parker.
Fatigue indices
As a person becomes fatigued, many body changes take place. In goine instances, the
changes have" merely beeii noted; in oft^era.'they have been used as measures of fatigue.
Table 20-1 hsts separately those indices WhiAare principally physiological and those which are
principally psychogenic or neurosensory. It should be understood, however, that these factors
are overlapping and interactive in the real-world situation. The table shows, in simpUfied terms,
the direction, either positive or negative, in which each index tends to move in the fatigued
individual. Again, this is a simplified interpretation and mttmftQtct flie iaewtable generaliza-
tions created by such an approach. For a given individual under a given set of drcumstanoes
supposedly producing operational fatigue, there is no assurance that each correlate wiU operate
in the prescribed direction as shown. Individual variability remains the rule rather than the
exception.
20-7
U.S. Naval Flight Surgeon's Manual
Table 20-1
Correlates of Fatigue
Physlolog ica l/B i ochemical
\Psychomotor/Neurosensory
Rectal temperaftire ♦
Reaction time ♦
Visual flicker fusion thresholds ♦
Watchkeeping ^
Strength ♦
Memory functions ^
Blood lactic acid
Communication functions ^
Blood glucose ♦
Nonverbal - mediational
Epinephrine ^
mental functions ♦
Norephinephrine
Decision making ♦
17-OHCS ♦
Tracking ^
Urea ♦
Peripheral and central detection
Potassium ♦
Subjective fatigue ♦
Cholesterol^
Auditory flutter fusion ♦
TrtgiycerideBi
Irritability ♦>
Plasma free fatty acids (FFA) ♦
Attention span ^
Serum thyroxin (T^) ■
Errors ♦
Corticosteroids ♦
Libido
Prolactin mm
Anxiety ♦
Growth hormone ♦
Recent memory ♦
Immunoreactive insulin ♦
Insomnia ^
Pupillary response time to light ♦
Cooperativeness
Binocular fusion ^
Depression ^
Visual accommodation time
Acceotance of criticism ^
to near and far points ^
Activities — hofabiufi Ptr
Muscle tonus ♦
Personal care ^
Electrolyte cutaneous excretion ^
Drug use ^
Circulating blood volume
Muscle glycogen ^
Neuromuscular coordination ♦
G^rointestinal efficiency ^
Eye^^ fatigue ^
Heart rate ^
(Adapted from Mohler, 1966). Published by permission o1 Av/ao'on, ^ace, and Environmmtaf Madlcine.
20-8
Fatigue
< )
The indices shown in Table 20-1 have been studied by many researehers. ifc rtJBtopts to
select those measures or classes of measrtfe^dk<iiire*ai:#li^ des&tibfc^t^e.
Sulijective AlBses^ttietiiB
An obvious way to assess the extent of opeW^iorial fatigue would be simply to ask a
crewman if he feels fatigued. But subjeetive information is not necessarily reliable, nor does it
always correlate wett with other, more objective measures of fatigue. Subjective information
elicited by means of a questionnaire is a weU-estabUshed technique that can yield vaHd, useful
answers (Perry, 1974). However, in the practical situation, rather than in research studies, it
should be understood that an individual may not cooperat e fidly, but, because of motivational
factors, may answer in sndi a way mm make bim8^^pear*is8 fatigued than he is.
A number of stiidies have used subjective fatigue reports together with more objective data,
for example biochemical determinations and tests such as critical fusion frequency and
performance measures. Grandjean, Wotzka, Schaad, and Gdgen (1971) examined fatigue and
stress in 68 air traffic contioUers using critical fusion frequency (CFF), lapping te«t, pid
tapping test, and self -rating. Stress in this stiidy ^as measured on the basis of a questionnaire
and on catecholamine excretion in the urine. All showed significant agreement. The authors
attached great importance to the self-rating questionnaire. It was their conviction that feelings
of fatigue as reported by the subjects were one of the most sensitive symptoms of fatigue.
Hartman, Hale, and Johnson (1974) stiadiedfatigur^lb-i^l cicwmemb^. Thcy dbMned
subjective reports and urine samples, and coUected preflight, midflight, and endflight data. The
subjective technique involved the use of a checklist and weighting factors and a simple test that
required subjects to indicate fatigue intensity by the position of a mark on a printed line of
standard length. The biochemical indices used were epinephrine, norepinephrine,
17-hydroxycorticosteroid8 (17-OHCS), sodium, potassium, and urea. Figure 20-2 presents the
results of this stiidy graphically. Ovet We 'gctirsfe-M tiie ei^t» ■imm:%mm'^rmH
than 100 pef^nt MlBSie^tf iii'te#^^ ratings for fatigue, inefficiency, and discomfort.
Two of the three hormones sampled, epinephrine and IT-hydroxycorticosteroids, sKowBd
increases similar to the subjective ratings,
Ayoub, Burkhardt, Coleman, and Bethea (1972) reported on tiie behavior of four subjects
working alternating schedules of eight and sixteen hours a day o^r w^gls. iM<i6d state
scales were administered, including a twelve-point fatigue scale at the beginning and end of each
of the twelve work days. The data indicated that the men were feeling no more fatigued at the
end of eight-hour days tiian at tiie beginning of those days, even though they were subjected to
four hours of ratiier demanding work on a treadmiU during each day. At the end of the
20-f
U.S. Naval Flight Surgeon's Manual
saxteen^hour day, with each day mcluding eight hours of treadmill work, the subjects reported
Mioie tfeffli-Nlite%g'«ii^h^%fl©i^ffl®j^©T*tt^<ifep^ average of almost one extra hour
of sleep prior to sixteen-hour days than hrfone ej|^l4iolir days, the average sleep time was well
below the eight hours often reported as optimum. In this study, however, psychomotor
performance showed no consistent decreflie|it even late in sixteen-hour days.
I
PRE- FLIGHT (CONTROL!
"lOFLfGHT I I SUBJ.
LATEFUBHT fFATISUE
POST flkhtJ I
j^mm wEFFieicitcY
■1 DISCOMFORT
(MID^FLThLATE)
IpRE- MISSION (CONTROL)
RECOVERY NIGHT )
I RECOVERr NISHT 2
}
SL£EP
DURATION
I EPINEPHRJNE
I NOREPINEPHRINE
1 1T-0HCS
[UREA
URINARY
>■ VARIABLES
IFB-111 ti CONTROLI
Figure 20-2. Graphic summary of all of the measures, using percent
deviation (%A). The control value for the etlbiep%e ratings and sleep
was the premisBion value. The contMl'Mttes for'ttfe ainlnary variables
were obtained from a separate group of flyers on a nonflying day
(Hartman, Hale, & Johnson, 1974). Published by permission of
Aviation^ ^xmyi^BmaymaetmMMieine.
Komedical Correlates
Numerous biomedicsal Cjorcelates of fatigue have been investigated, and a number of studies
have attempted to combine biomedical and performance criteria, hi l^Mon to fati^e in both
the operational and laboratory setting. The biomedical correlates principally examined are heart
rate and biochemical indices, notably in the latter case, urinary metaboKtes and hormones. The
reader is referred to Table 20-1 for a partial Usting of physiological and biochemical parameters
which have been dealt with in fatigue studies.
Miller (1968) reviewfil stujie^ dealing with secretion of 17-hydroxycorticosteroids in
miUtary aviators as an index of response to stress. This author concluded on the basis of a
review of 40 research efforts that several generahzations could be made. Increased adrenal
corticosteroid secretion occurs m response to flight factors such as danger, duration of
.exposure, degree of responsibility, and experience level. Changes in plasma, urmary, and parotid
2010
Fattgue
fluid 17-hydroxycorticosteroid concentrations have been shown, he states, to be an excellent
index for the evaluation of stress. It should be noted, however, that the stress bemg dealt with
wm of mtm i^& imtiA in ti? ©tfmbat dtuatiotis. While fatigue ufiddUbtedlf^iifi^t'ii
the biochemical respHfijSl, f aftfcatolSf mMmA the eisd of the miisiGnS^ sfecretion of 17-OHCS is a
dglid of '*gfaierd adaptation syndrome." If Selye's model of human physiological response to
Stre^ (1950) is accepted, three stages of response occur. These are an alarm reaction, a state of
resistance in which adaptation occurs (the period during which 17-OHCS secretion peaks), and a
stage of exhaustion in which adaptation is lost. Where fatigue supervenes, the in^#<3ti^>£M^
expected to be in the tMrd stage of response to Stress, wherein the acute stress adat>tation
response may or may not be called up, depending upon the extent of fatigue.
The study by Grandjean et al. (1971) was discussed in conjunction with subjective
assessments of fatigue. It indicated that fatigue and stress in air traffic controllers was correlated
with an increase in catecholamine excretion in the urine. TableJSO-3' AttfiW
catecholamine/creatinine in fi© nrine ^ si« -tt *tR«iie cottttaBte The table eoittpaies
catecholamine responses during office work, grOund tafafHe cfJttti^lf awd air teSffie control. An
analya* of vsaiance showed that there was a significant (p<0.05) difference between the results
during office work and ground traffic control on the one hand and air traffic control on the
other. The authors do not indicate the length of time each subject was involved in the various
types of tasks. These biochemical responses may, therefore, be more related to acute stress#[fln
Uiey are to fatigue, but they are necessarily related in some measure to both.
Table 20-2
Catecholamine/Creatinine in the Urine of 6 Air Traffic Controllers
(iLig Noradrenaline + Adrenaline Per 100 mg Creatimne)
Subject
No.
During Office
Work
During Ground
Traff ib ddhtliSl '
During Air
TfSfffe Control
1
48
46
62
2
47
58
80
3
39
49
58
4
46
40
87
5
54
n
' 40
3$
51
126
Mean values
45.5
52.5
77.0
(Grandjean, Wotzka, Schaad, & Gilgen, 1971).
20-11
U.S. Naval Fli^t Surgeon's Manual
Dukes-Dobos (1971) reviewed studies concerning fatigue from the point of view of urinary
metaboHtes. The urinary excretion of proteins, electrolytes, and hormones is believed to be
isolated to fatigi^v ^IMa^^pew <e@iieKid^^^ l^fa^efj^liih^d
between the excretion of any of these substance iijd fatigue, pife^|t|^;|«|^pii|B.Sf li^^dual
variability manifest both in the magnitude of response and in the direction of jtegponse. Studies
of these metabohtes are further confounded by difficulty in controlling other variables
including circadian rhythms, food and fluid intake, the volume of urine excretion and sweat,
climatic conditions, time intervals between samples, and the subject's state of acclimatization,
tlsMifflE>F experience. ,i v ,
Froberg, Karlsson, Levi, and Lidberg (1972), in a study of circadian vmations in
psychomotor performance, subjective fatigue, and catecholamine excretion during prolonged
sleep deprivation, found epinephrine excretion to be positively correlated with performance and
negatively mii^%d with subjective feeKnga of fatigue. The reverse relationship existed for
m®i!ifiMphEine. Ffankenhfeuser, MeUis, Risslerv Bjodcvall, and Fatkai (1968) found a ppsitrare
relationship between ^epinephrine release rate and perfeinnance effiden^ to atuaWons
characterized by monotony and understimulation. These investigators noted that objective
performance and subjective reactions differed greatiy in persons who differentiated on the basis
of epinephrine output. High catecholamine output was associated with high performance
I ] , •'. 1 .. . , ■ ,1,1,.
A later study by Hartman and co-workers (1974) also examined urine samples in
bioraedicaJly dedicated missions (15) of eight hours duration in the F-111 aircraft. To recap
briefly, epinephrine, 17-OHCS, urea, and potassium were all significantly elevated in the two
crews for whom biochemical determinations were made. The values were relatively high and
wmi indicative of physiological stress of a moderately high degree. Interestingly, the range of
silbjective fatigue scores^ this study is typical o| transport crews whose missibns are not nearly
as demanding as those flown by the F-111 crews. The excellent flying characteristics of the
aircraft may well have been an offsetting factor in perceived fatigue.
In a recent study, Fobs, Shmukler, Wyeth, Contreras, and Valeri (1976) searched for a rapid,
noninvasive, pljective molecular indicfitor of the e^augltioA lotf the body*s adaptive mechanisms
and the oii8e|^f patholo^. He and his co-workers found that free^radical-forming compounds
in urine, identified by electron^^in resonance (ESR) spectroscopy, increased sipificantiy in
volunteers centrifuged to grayout. They also observed a positive correlation between
acceleration tolerance and the level of free radicals detected, i.e., those subjects with the highest
tolerance exhibited the lowest ESR signals.
20-12
Fatigue
It was found that the free-radicai-forming compounds in urine could be concentrated
through a process in which these substances were adsorbed by percolating urine through a
column of XAD-2 resin. After washing with water to remove all salts, etc., the free-
radical-forming compounds could be eluted with methanol. The authors felt that this procedure
might lend itself to the development of rapid, simple chemical tests for molecular discriminators
and achieve a reliable bioindicator of stress, adaptable to field use.
Psychophysiological Correlates
Another avenue followed by many investigators in fatigue assessment is the correlation of
psychophysiological measures with performance decrement. Recent research has employed
critical flicker fusion frequency, bUnk measurement, pupil diameter, and auditory flicker fusion
as indices of mental fatigue. These methods are by no means representative of the scope of
indices which have been applied. They are purely exemplary of the types of psychophysiological
measures used in this field.
Fukui and Morioka (1971) used a blink method to asse^ fatigue. The assumption upon
which the validity of such a measure is based is that a moving object is best recognized by
looking with repeated rapid blinks as compared with the usual method of looking. Blinking is
associated with the function of the eyeUds and oculomotor muscles, retina, optic nerve, and
cerebrum. Bhnk value may then be an indication of the total functioning of these organs and of
the autonomic nervous system. The blink value test can be performed within 30 seconds with
high accuracy and sensitivity, giving a measure of autonomic nervous system function and
allowing accurate estimation of the fatigue state of the whole body, according to the authors.
The method involves the use of a revolving board bearing a pattern with a constant size and
color. The maximum rotation speed at which one can recognize the pattern by looking with
repeated rapid blinks is measured by gradually decreasing the rotation speed. The value of the
maximum rotation permitted is called the blink value.
Under conditions of very hard work, work in high temperature, insufficient sleep, and
malnutrition, a decrease in bhnk value day -by -day was observed (Fukui & Morioka, 1971). This
is illustrated in Figure 20-3, indicating accumulation of fatigue. Moreover, the blink value
showed a decreasing curve similar to that of urinary excretion of total 17-OHCS.
Discussion ,
Operational fatigue is a term applied to the type of fatigue which appears in individuals
subjected to arduous work, stress, irregular schedules, and more-or-less constant pressure
extending over a number of days. Many events in naval aviation, including periods of training,
20-13
U.S, Naval Fli^t Sutgeon'a Manual
inspections, and combat, include all of the ingredients which can tead to operational fatigue.
Whether operational fatigue in fact occurs, and whether it then is a serious matter to be dealt
with, is not a clear-cut issue.
200
UJ
D
150
<
>
z
100
-1
m
50
3
DAYS
Figure 20-3. Daily change of the hhnk value indicating
the accumulation of fatigue (Fukui & Morioka, 1971).
The most compelling evidence for the existence and importance of operational fatigue
comes from invetfgationfl of aircraft accidents in which pilot fatigue is identified as a primary
C9^e, There are mioiy such accident reports, far too many for the ii^e of
fatigue to be ignored. The following summary of a Traiiung Command accident is illustrative:
' ' Hie student pilot had had only three meals in two days
before the accident and only one could have been considered
well-balanced. His last meal, 23 hours before the accident,
consisted of a cheese sandwich and a soft drink. The pilot's sleep
I had been as inadequate as his food. The ni^t before tile fligfit he
had slept for only four and one half hours. On the day of the
accident, he had been awake for 14 hours and on duty status for
12 of these. To liiake matters worse, bad weather delayed his
takeoff for six hours.
The scenario leading to the accident described above brings in all of the classic factors leading to
operational fatigue.
While accident reports frequently mention fatigue as a cause, other approaches to the
fatigue problem do not provide such a clear-cut picture of the relationship between fatigue and
performance. Field investigations, in which work is continued over some long period of time
20-14
Fatigue
and performance continually monitored, generally show that perforntance by healthy,
highly-motivated subjects can be maintained quite well, even with greatly increased subjective
reports of fatigue. It obviously is quite difficult to identify the point at which fatigue will cause
a dangerous deterioration in performance simply by talking to a person.
To search for more objective indices of fatigue also produces conflicting reisults. Th^ search
for biochemical measures of fatigue is based on the assumptioft that people show a consistent
and measurable change in body chemistry related to their present state which can be used as a
predictor of tlie amount of work they can reasonably be expected to do in the near future
(Perry, 1974). Although biochemical measures have shown changes following prolonged
physical exertion, the assessment of flie effects of mental or perceptual tasks has so far not
produced techniques that can be applied in the field situation. Also, studies have i^own wide
differences in the biochemical responses of different individuals to working conditions, and in
the response of one individual to a given working situation on different occasions. Perry, acting
as spokesman for the AGARD Aerospace Medical Panel Working Group on Helicopter Aircrew
Fatigue, takes these findings to mean that, at least at the present time, any sin^e biochemical
measure or any coltection of sijch meamires is of Uttte diagaostic value. He dojes, howeii^rj,
recommend that the search for biocheinical correlates of fatigue be continued.
Role of die Fli^t Siu^eon
A Flight Surgeon is in a unique position to deal with operational fatigue, principally because
his orientation is more dfeectly toward the safety aspects of the situation than anyone else's.
Senior personnel are concerned with mission accomplishment. Aviation units are graded in
terms of number of sorties flown and the results of those sorties. Although safety is never
ignored, the main objective is mission accomplishment. If more hours need to be flown in order
to accomplish a mission, those h<*ur8 wiH b? flown.
Aviators themselves are not in a good position to evaluate operational fatigue. Pressures
from superiors, peers, and "self-image" aU combine to make it most desirable to press on with
the last ounce of reserve energy rather than to ground one's self because of excessive fatigue.
A Flight Surgeon, because he is the only individual in a position to judge the general fitness
of an aviation unit with some objectivity, bears certain ressponsibilities toward that unit. The
following sections describe those actions appropriate for a Fli^t Surgeon in dealing with
operational fatigue.
20-15
U.S. Nava! Fli^t Surgeon's Manual
Monitoring of Operational Units
It is a relatively simple matter to trace the antecedents of an accident and to record the
amount of sleep within the last 48 hours, the time since a last nourishing meal was eaten, and
the number of timeis a scheduled missioii was cancelled or shifted. With appropriate data, one
can clearly make the case for operational fatigue as an accident cause. It is much more difficult
to evaluate onp;oing events and decide when operational fatigue has buUt to the point where
individual safety and mission proficiency are jeopardized. Yet, a FKght Surgeon must attempt to
do this. This means that he must be in touch with aviation units during periods of extended
activity, must observe the day-to-day condition of individual aviators, and must be prepared to
reconuaend grounding wheai he thinks fatigue has become excessive and dangerous. It is more
important to prevent tiie accident than to describe it.
Seep Sdiedule
Proper rest can do much to stave off the cumulative effects of operational fati^e. While
sleep schedules arc of lower priority than mission assignments, a FUght Surgeon still can do
much to help the situation by bringing the need for appropriate rest periods to the attention of
command personnel. Information is available as to optimum work-rest schedules. Woodward
and Nelson (1974) reviewed the literature on the effects of sleep loss, work-rest schedules, and
recovery on performance, and they recommended the following schedules for different
operational conditions:
Duration of Sustained Work. Work-rest schedules of
"2 on - 2 off," "4 on - 2 off," "4 on - 4 off," "6 on - 2 off,"
"6 on - 6 off," "8 on - 4 off," and "8 on - 8 off" can be main-
tained equally well in terras of performance decrement for
periods up to five days.
Work-rest schedules of "4 on - 4 off" and "16 on - 8 off"
can be maintained equally well in terms of performance
effectiven^ass for periods up to two weeks, provided no period of
acute sleep loss is experienced.
For periods greater than two weeks and wp to 30 days, a
"4 on — 4 off" schedule is superior to a "4 on — 2 off" schedule
in terms of performance effectiveness.
Performance Under Stress. Under stressful conditions,
"4 on - 2 off" and "6 on - 2 off" schedules tend to result in
poorer performance than do schedules which allow longer
off-duty periods.
20-16
Fatigue
Performance Recovery /Adaptation. If an acute sleep loss
period greater than 24 hours is experienced after working on a
continuous work -rest schedule of "4 on - 2 off " or
"16 on - 8 off," the "4 on - 2 off" worker is more likely to
show performance impairment and will return to baseline , 7
performance more slowly.
Adaptation of biological rhythms to an atypical work-rest
seMdle' requires, ©11 tiie «r#«ge, a ikfiee- to fewr-ive^ tim)^
period. ... , .. ' ,
Contributing Agents
There are many forces in the aviation environment which can add to operational fatigue m
the seme of making an aviator less able to handle fatigue than should he the ease* S0te# of tteeie
are inadequate ij^et smdiEPepkr meal echedtdm, oriflttprcjpefl^^^ed iqulpftiw^
personal diffieultifes, and pobif' physical condition. Td'fllfe l^lentift|irii«e Stllinilar problems
are observed, a Flight Surgeon has a responsibflity to a «sttfe%tivt prbpfflK and to be em
more alert for the onset of operational fal^e.
References
Ayoub, M.N., Burkhardt, E., Coleman, G., & Bethea, N. Physiological response to prolonged' ifliSiMifte'kctivity.
In D. C. Hodge (Ed.), Military requirements for research on continuous operations (TM 12-72). Human
Engineering Laboratory, Aberdeen Proving Ground, Maryland, 1972.
Brictson, C.A. Pilot landing performance under high workload conditions. Prepared by Dunlap & Asso-
ciates, Inc., under Contract No. N00014-73-C-0053 for the Office of Naval Research. Arlington, Virginia,
April 1974.
Dukes-Dobos, F.N. Fatigue Irom the point of view of urinary metabolites. Ergonomics, 1971, 14(1), 31-40.
Frankenhaeuser, M., MeHia, I., Rissler, A., Bjorkvall, C, & Patkai, P. Catecholamine excretion as related to
cognitive and emotional reaction patterns. Psychosomatic Medicine, 1968, 30, 109.
Froberg, J., Karlsson, C.G., Levi, L., & Lidherg, L. Circadian variations in performance, psychological ratings,
catecholamine excretion, and diuresis during prolonged sleep deprivation. International Journal of
Psychobiohgy, 1972, 2, 23.
Fukui, T., & Morioka, T. The bKnk method as an assessment of fatigue. Ergonomics, 1971 , J 4(1), 23-30.
Grandjean, E.P., Wotzka, G., Schaad, R„ & Gilgen, A. Fatigue and stress in air traffic controllers. Ergonomics,
1971, 14(1), 159-165.
Hartman, B.O., Hale, H.B., & Johnson, W.A. Fatigue in FB-111 crewmembers. Aerospace Medicine, 1974,45,
1026-1029.
McFariand, R.A. Understanding fatigue in modem life. Ergonomm, 1971, 14(1), 1-10.
Miller, R.G. Secretion of 17-hydroxycortix:osteroids (17-OHCS) in military aviators as an index of response to
stress: A review. Aerospace Medicine, 1968, 39(5), 498-501.
Mohler, S.R. Fatigue in aviation activities. Aerospace Medicine, 1966, 37, 722-732.
20-17
U.S. Naval Flight Surgeon's Manual
ODonnell, R.D., Bollinger, R., & Hartman, B.O. The effects of extended missions on the performance of
airborne command and control teams: A field survey (AMRL-TR-74-20). Aerospace Medical Research
Laboratory, Aerospace Medical Division, AFSC, Wright-Patterson Air Force Base, Ohio, July 1974.
Office of Naval Research. Final report: Naval aviation, biomedicine, and human eff«ctiveneB8 technical
workshop. (Contract No. N00l4-73-C-(Ml(S2). Office of Naval Research, fittfeau of Misdicine and Surgery.
Washington, D.C., 1973.
Perry, I.C. (Ed.). Helicopter aircrew fatigue (AGARD Advisory Report No. 69). Advisory Group for Aerospace
Research and Development, North Adantic Treaty Organization, May 1974.
PoHs, B.D., Shmukler, H.W., Wyeth, J., Contreras, T., & Valeri, R. Udqae free ladioal C«nipoiieittS ui niitie as
won-invasive indicators of stress intolerance in humans. Preprints of 1976 Annual Scientific Meeting,
Aerospace Medical Awociation, Bal HaAour, Florida, May 10-13, 1976, 247.
Selye, H. TTte physiology and patkohgy of exposure to stress. Montreal: Acta, Inc., 1950.
Shannon, R.H., & Lane, N.E. A survey of major P-3 accidents with special emphasis on fatigue. Patrol ASW
Devslopment Group Report Number 40 prepared for the Commander, Fleet jWr Wings, U.S. Atlantic Fleet,
Heit Afe Wing Five. Norfolk, Virginia, March
mm, V.R., Every, M.G., & barker, J.F., Jr. I/.S. mod aerospace physiologist's manuta (NAVAIR 00-80T-99).
Bureau of Medicine and Surgery, Department of the Navy. Washington, D.C., September 1972.
West, V.R., & Parker, J.F., Jr. A review of recent literature: Measurement and prediction of operational fatigue.
Prepared by BioTechnology, Inc., under Contract No. N00014-74-C-0225, for the Office of Naval Research,
Department of the Navy, ^xlington, Vi^inia, Felwaary
Woodward, D.P., & Nelson, P.D. A user oriented review of the literature on the effects of sleep loss, work-rest
schedules, and recovery on performance (ACR-206). Office of Naval Research, Biological and Mescal
Sciences Division, Physiology Pro-am. Ailington, Virginia, December 1974.
20-18
n
o
o
CBAPnit 21
THERMAL STRESSES AND INJURIES
Introduction
Thermal Equilibrium
Hypothermia
Hyperthermia
Indices of Thermal Stress
References
Bibhography
Introduction
In his continuing attempt to master his environment, man has circumvented his
phylogenetie heritage as & tropical mammal by developing a sophisticated technology which
permits him to eottfxol the tempeMture, humidity, and pressure af his immediKte suirouniliijgs
in jm almost routine manner. However, for the aircrewman, in-fli^t emecgenciei or enemy
action remain ever present hazards, and a situation may develop almost instantaneously which
may force him to survive the rigors of exposures to extremes of temperature or cold water
immersion. Ground support personnel must frequently hve and work under simitar adverse
enviroimiental conditions, and maintenance of their functional effectiveness both ashore and
sB^OBt k an area, of concern to titie Fli^t Surgeon. Therefore, it is incumbent upon the Flight
Surgeon to imderstiqid the vaiioui operational, clinical, and preventitive medicine interrela-
tionships of environmental thermal stress.
Man's response to environmental extremes of temperatures had been of interest prior to his
early attempts to fly. His response to climate influenced his geographical migrations and cultural
development. It was realized even before commencement of modern tropical and polar
explorations and subsequent naval operations that an individufd's ability to lead a heidthy and
productive Hfe in such envminments was problematic. Althou^ it is nearly impossible to
divorce completely the physiological effect of teniiierature ^^tremes from th^f p^holb^cal
effect, this chapter will consider primarily the former.
Because all mammals are homeothermic organisms, maintenance of the internal body or
"core" temperature within a minimal range of variation, independent of ambient temperature, is
21-1
U.S. Naval Flight Surgeon's Manual
the major factor responsible for the normal pattern of biodiemieal reactions in man. The
biochemical reactions responsible for metabolism impose several requirements upon the
mechanisms regulating body temperature. Since most biochemical reactions are effected
through the action of enzymes, which are particularly sensitive to temperature change, a fall or
rise of only a few degrees in core temperature may so retard metabolism that normal behavior is
impossible and death may ensue* In the course of biochemical oxidations, heat is liberated, and
unless provision is made for its dissipation, overheating of the body may occur. This could cause
death as a result of irreversible damage to the various enzymatic systems and cells of the central
nervous system. It is mandatory, therefore, that thermal equilibrium of the body be maintained.
Thermal Equilibrium
Thermal equilibrium is preserved by the body's ability as a whole to alter its rate of heat
production and heat loss. Since body temperature is really a measure of heat content or storage,
a faU in temperature indicates a decrease, while a rise denotes an increase, in the total heat
content of the body. Althou^ the core temperature varies normally over a range of only a
single de^^, the variation in temperature of ib© exposed portions of tiie body reflects its
conitinual effort to achieve equilibrium. First, the rate of heat production and then, the rate of
loss are altered by environmental and/or physiological changes. A normal sized, unclothed man
at rest in a postabsorptive state can, with minimum body effort, reach thermal equilibrium at a
room temperature of 86°F (30°C). Under such conditions,' the individual retains only that
amount of heat formed by his basic metaboSc processes which comprisel normal storage. He
loses the remainder to the environment without utilization of any of his reserve mechanisms of
heat loss. The preceding example is only one instance of countless states of thermal equilibrium.
Its significance lies in the fact that no reserve mechanisms of heat production or heat loss are
required to achieve equilibrium. Under different conditions of clothing, activity, or environ-
Metit, additional physiological adjustments would be needed tij maitttaili £tft eqdi^filettt state.
Mother expression of thermal equilibrium has been designated as the "comfort zone." The
comfort zone mav be grossly defined as the set of environmental conditions which causes
neither sweating nor shivering. A more precise specification is possible through reference to the
Effective Temperature (ET) Scale, which has become an accepted index of environmental
comfort.
J
A scale of effective temperature may be presented (Figure 2I-I) as a family of curves
formed by a plot of all combinations of relative humidity and temperature that yield the same
subjective sensation of temperature. It is generally agreed that the optimum comfort range for
^persons wearing normal indoor clothing is +65^ to +73° ET. As can be seen, this corresponds
ronghty to a temperatuf© range between +^0 ^d,+$0°F with relative huinicUty betwejen 40 and
2Xr2
Tliennal Stresses and Injuries
60 percent. Although in practice the Effective Temperature Scale has been lound workable, it
should be noted that the stated comfort range will be altered as a function o( any variation in
amount of clothing worn, level of physical activity, and with the introduction of the factor of
air movement.
Heat Transfer
Heat is transferred to and from the body by several different physical processes — radiation,
conduction and convection, and the vaporization of water.
Within the body, heat is transferred from the core to the shell or skin surface primarily by
conduction and convection. The agent of transport is the circulating blood. Therei'ore, thermal
r^ulation is dosely relatfed to the regulation of peripheral circulation throu^ the cutaneous
vascular bed, particularly of the extremities, since they represent about 65 percent of the total
body surface. At certmn times, as mudi as ten percent of the total Mood volume of the body
may be located in the skin, within a surface layer only two millimeters thick (Krog, 1974). The
mechanisms by which circulatory control is accomplished either to preserve or dissipate heat are
21-3
U.S. Naval Flight SurgeoR's Manual
many and complex. These mechanisms are mediated both centrally and locally and include
yascular dilation and constriction, arteriovenous shunts, cold-induced vasodilation, counter-
earrent exchange, and cold adaptation. The existence, as well as the relative importance, of
some of these mechanisms, however, has been challenged.
Radiation. Radiation is the transfer of heat from the surface of one object to another
without physical contact between the two. The magnitude of heat loss in man is directly
dependent on skin surface area and the average temperature grjidient between the skin and
surrounding objects. The heat loss from radiation varies widely with environmental conditions.
La a temperate chmate, a resting individual, wearing ordinary clothes, loses about 60 percent of
his heat production by radiation. At a temperature of 90°F> this loss may drop to zero.
Conversely, at subzero temperatures, heat loss by radiation msy reach levels higher than
60 percent.
Conduction and Convection. Conduction and convection are less important methods of heat
loss in temperate climates but assume major roles in polar climates. By conduction, the cold air
in immediate contact with the skin is warmed; the heated molecules move away, and cooler
ones approach to take their places. These in turn are warmed, and the process perpetuates itself.
The air movements constitute convection currents. Any process, such as wind, which tends to
increase the rate of movement of the ambient air relative to skin surface intensifies keat loss.
The phenomenon has been incorporated into the concept of windchiE by Siple and Passel
(1945). Aunit of windchOl is defined as the amount of heat that would be lost in an hour from a
square meter of exposed skin surface which has a normal temperature of 91.4^F. Given a
hypothetical situation wherein the wind velocity is 20 miles per hour and the temperature
is 34*^ F, reference to the Windchill Chart (Figure 21-2) discloses that at the given wind and
temperature conditions of the hypothetical situation, the rate of cooling of aU exposed flesh is
the same as at minus B8^¥ with no wind. It is easily concluded that under the climatic
conditions observed, in polar operations, conduction and convection are significant causes of
heat loss and potential contributory factors in the causation of cold injuries.
Heat loss by conduction also occurs from transfer of heat to tidal air as it is warmed in the
respiratory passages and lungs, to water and foodstuffs taken into the gastrointestinal tract, and
t& wSiste' materials (urine and feces) as they are ehminated.
V^orixation of Water. Vaporization of water removes heat fi-om &e skin surface aaad the
moist mucous membranes of the respiratory epithelium. When one gram of water is converted
into water vapor, 0.58 kilocaloiies of heat must be supplied from the surroundings for the
COnvfOSKttt to occur. Although the actual amount of heat loss depends on the ambient relative
humidity, in Antarctica, where humidity is very low, respiration alone may account for
21-4
Thermal Stresses and Injuries
ten percent (375 kcal) of an individuai's total daily heat loss. Insensible perspiration, as is shown
in a later section, accounts for an additional loss of about 400 kcal.
Ko = ( vW X 100 - WV + 10.5) (33 - Ta)
WIND VELOCITY
Tiile5.4ir meters/sec
5-
4
3 -
35
30 -
20 5'°
0.5
OA
0.3
TEMPERATURE
°c
-so-i
-60
-70-
-55
.60-
-SO
-50-
■ts
,4fl-
-40
■30-
..35
.20-
—30
.10-
- 4S
-.20 .
0-
■ '15
10-
-10
20
- -5
30-
- 0
40-
. s
50
- ID
60
■ 13
70
- 20
\^ 80
' - 25
- 30
Figure 21-2. Windchill nomogram
(after Blocltley, 1964; adapted from Sipple & Passel, 1945).
.1/
Loss of heat by vaporization of perspiration from eccrine sweat glands may account
for a large part of the total heat loss at temperatures of 93° to 95**F, or above, but in
polar cliinates, it assumes importance only under certain clothing conditions wMch wfll J}6
discussed later.
21-5
U.S. Naval Fli^t Surgeon's Manual
It can be seen, then, that loss of heat from the body occurs primarily at two surfaces, the
skin and the epithelium of the respiratorj- system. Under constant environmental conditions,
the amount of heat loss depends upon surface area, temperature gradient, humidity, vapor
pf^sure gradient, and the rate of airflow over the surface.
Heat Regulation in Cold Environments
i^ysioh^cal Mechanisms to Dimmish Heat Loss. Some of the physiological methods used
to diminish heat loss in lower mammals art; unsuitable or impractical for man. SuCh procedures
as rolling up into a ball and thereby markedly decreasing the area of exposed skin, or
diminishing heat loss from vaporization of water at respiratory surfaces by cessation of panting,
obviously have httle application to human beings.
Since approximately 80 to 85 percent of heat loss occurs from the body surface, any
reduction in skin temperature slioiild consen e body heat. Changes in the temperature of body
surfaces are mediated through the a<;tivity of three physiological mechanisms. Unfortunately,
one of the three mechanisms, although of some value in retaining body heat, is of greater
importance when heat dissipation is desired.
The first mechanism depends upon the means by which heat is transported from the depths
to thjB surface of the body. Blood is 80 percent water by volume; because of the water's high
heat capacity, circulating blood is tlie primary source of heat transfer to the body surface. The
total amount of heat brought to a given area is a function of the rate of blood flow through the
area. If the rate of flow is retarded by local constriction of the superficial arterioles, the total
heat transfer from blood to skin tends to be small and the skin remains cool, thereby decreasing
the temperature gradient between it and the surrounding cold m. Although thfe physiological
mechanism is an important means of heat conservation, a certain minimum blood flow must be
maintained through the skin to prevent localized anoxia and ceUular death.
The second mechanism is dependent on the phenomenon of horripilation, or erection of
body hair, which increases the thiekne^ of the layer of nonconducting air entrapped between
the hairs, SinCe surface temperature depends upon the ease with which heat fe transferred from
the body to the environment, horripilation affords a satisfactory method for retiffding
conduction by reducing the temperature gradient between the skin and environment even
though the skin temperature may remain at a high level. Due to evolutionary processes, man is
poorly equipped to take advantage of horripilation. Nevertheless, he utilizes the principle by
soh^tuting a different insulating material, clothing, for the hair he lacks. A single layer of
clothing limits heat exchange by replacing the single temperature gradient between a nude
subject and his envirorunent with three such gradients. One of these three exists between the
21-6
Thenaal Stxessesjuid Injuries
skin and the inner surface of the insulation, another exists between the outer surface of the
insulation and the environment, and the third gradient is found between the inner and outer
surfaces of the insulation. The effectiveness of clothing in decreasing heat loss is proportional to
the magnitude of this third gradient, which in WW defieudg upoir the nature and thickness of
the nonconducting subsfeMce. / *
A third mechanism modifies the temperature of body surfaces by varying the amount of
moisture available for vaporization. Since insensible heat loss due to perspiration is not subject
to wide variation in cold climates, the primary value of this mechanism is in the dissipation of
body heat rather than its retention. ^ , ;
Beat I^oiAiction. Wheiir. fe^t loss exceeds heat production in spite of utilization of the
pre\iously discussed physiologic mechanisms, the body, in an effort to regain thermal
equilibrium, increases heat production. Heat production is essentially chemical in nature and is
developed from at least two different sources. When body temperature decreases in a resting
human exposed to cold, involuntary muscular contractions (shivering) ensue. Since pnly
25 percent of Ihe energy ]S)erated by chemical changes iri contracting' muscle is converted to
work, heat production is equivalent to three or four times that of the muscle at rest. Even more
efficient in heat production than isotonic involuntary exercise is voluntary isometric exercise
(contraction of both extensors and flexors simultaneously) which converts all of the energy
produced to heat. , .
Another source of heat produ^on which does not involve skeletal muscle contractioite has
been demonstrated by various investigators in animals. Small experimental animals Uke the rat
are able to vary their rate of heat production within several hours by some mechanism in which
the hormones of the thyroid gland, the adrenal cortex, and possibly the adrenal medulla
participate without any detectable change in either voluntary or involuntary muscular activity
(Davis, 1963). This non-shivering thermogenesis is produced by increased tissue sensitivity to
norepinephrine, and the small amount of subcapsular brown tissue plays an important role in
this mechanism. Eecent research TO^tsts tixat .Qlh# ti^#' juis^^4^i^^
cold acclimatized animal is mediated through an intermediate mechanism in the brown fat
tissue. Although Davis (1963) suggested that non-shivering thermogenesis also exists in man,
man has no brown fat tissue, and non-shivering thermogenesis does not seem to occur to any
significant extent in mammals larger than the rabbit (Jansky, 1969).
Those regulatory responses discussed above can succeed in maintaining thermal balance for
hours within the compensable zone. Figure 21-3 shows the approximate limits of the
compensable zones on both sides of the comfort zone. When temperatures fall below the
21-7
U.S. Naval tiS^t Borgeoia^ Manual
compensable zone for cold tolerance, thermoregulotlbil fitt Md extraneoixg methods notUSt
be utilized to maintain dermal balance. ' ' '
VAPOR PRESSURE -mm Hg
Figure 21-3. Representation of comfort zone and compensable zones
(Webb, 1961).
Heat Regulation in Warm Environments
Physiological Mechanisms. As the body becomes heated, whether it be from exposure to a
high temperature environment, physiologic exercise, or a combination of both, aiperficial
vsi6dilaii6# bd^i«, thcb^by increasing blodfl flb# to lite ^kin. His dlow&additibttlit tieatto be
kaet {>ttom% by cofiibctton and i^diatton. Fuilheiiia'ibb^, heat is IbM through ittietffidble
jptttpiration aiid tedjpSlfatlon. When the body becomes heated beyond the limits of Hie comfort
range, these processes are insufficient to maintain thermal equilibrium.
A second response to heat exposure is an increased rate of excretion by the eccrine glands.
Through the evaporation of water produced by sweating, a large increase in the rate of heat loss
pan be realized. Although the body can produce sw^at at a high rate, evaporative heat loss is
litnitied by the physical process of evaporation, which, in turn, depends upon skin temperature.
Thermal Stressee and Injuries
water vapor pressure gradient, and movement of the air surrounding the individual. The vapor
pressure gradient is defined as the difference between the water vapor pressure at the skin and in
the surrounding air.
Effects of Cki^Utg. Thermal comfort land stability are moclified considerably by the
clothing an individual wears. With suitable clodung, a person can achieve a level of comfort and
survival over a much greater range of environmental temperatures than those shown in
Figure 21-3.
Heat transfer throu^ clothing is a function of the thermal resistance of the clothing and the
temperature and humidity differential between the itmer and outer surfaces. Thermal resistance
of clothing is expressed in terms of "clo" umts. One clo is defined as the equivalent to no^al
indoor clothing and is that clothing insulation required to keep a resting/sitting man with a
metabolism of 50 kcal/m^/hr. indefinitely comfortable in an environment of 21*^0 with an air
movement of 20 ft./min., and with a relative humidity of less than 50 percent (Kerslake, 1965).
The insulation value of clothing is a function of the air trapped between its fibers and is roughly
equal to four clo per inch thickness of fabric.
The biophjfsics of clothing has become singularly significant in recent years because it is an
interdisciplinary approach (physiology, psychology, physics, clothing design, and textile
science) which relates human work efficiency and comfort to a specific task in a particular
environment Prior to this realization, tiie physiologist was consulted for informatiott about the
man, and the cHmatologist was sought out for knowledge of the environment. Little was known
about the physics of how clothing materials interacted with each other or with the complex
man-(;lothing-environment system. Most experimental measurements utilized "steady state"
conditions for simplicity and the reduction of variables. Utilization of the biophysical approach
should result in an end product clothing system in which man, environment, aftd clothing are
united into a functional and comfortable whole.
In a cold environment, an individual frequently finds himself wearing more insulation than
he needs during work and less than he needs at rest. This is readily explained by considering the
biophysics of the situation. For maintenance of thermal equilibrium in any ^ven environment,
the optimum insulation is five to six times as much at rest aS at work. The problem, then, is to
design clothing which optimizes the balance between static and dynamic insulating efficiencies.
Specifically, the rate of heat loss must be minimized when activity level is low and increased
when activity level rises.
Primary functions of protective clothing are to insure adequate ventilation for the escape of
both insensible and sensible perspiration, and to provide, around the body, an insulating zone of
21-9
U.S. Nfival Eli^t Surgeon's Manual
dead airspace which is compartmentalized in sufficiently small pockets so that currents of air
will not be set up by movements of the body and thus disperse heat.
Polar explorers have cautioned repeatedly against the danger of sweating profusely because
during later periods of diminished activity, excessive heat loss occurs when the vaporized
perspiration condenses on the cold outer cloth, thereby permitting direct heat transfer by
coiiducfSon. Because retention of vaporized perspiration in clothing diminishes the effectiveness
of the sweat mechanism in cooling the skin surface, increased production of perspiration ensues
and a potentially dangerous situation develops.
Conversely, in hot environmmts, clones beconie abarriier to the enraporatidn of perspiration
ttom the skin because sweat evj^orated from wet clotting is much less effective in removing
'heat from the body than moisture evaporated directly from the gldn.
Figure 21^ illttstrates the interaction of clothing insulation, activity, and ambient
temperature in the maintenance of thennal balance.
14 I ■■ ■ 1
100 80 60 40 20 0 - 20 - 40 -60
AMBIENT TEMPERATURE CF)
Figure 21-4. Prediction of the total insulation required for prolonged
comfort at various activities in the shade as a function of ambient
temperature (Moi^an, Cook, €hapaidB, & Lund, 1963).
21-10
Thermal Streeses and .Injuries
Hypothermia
When heat loss exceeds heat production, hypothermic injury may develop. Hypothermia is
classified as general or local, depending on whetiier the injury affects the individual as a whole
or affects only a particular part of the body.
t
General Hypothermia ]
Accidental general hypothermia may result from total or partial imE|ersion m cold water or
from exposure to cold ambient air temperatures alone. It is most frequent cold injury seen
in aviation medical praettee afloat. Almost four-fifths of tiie world's surface is covered with
water, and apart from ihe equatorial regions, ^e temperatures of the world's seas are
substantially below body temperature. Deck personnel and particularly aircrewmen who fly
above these waters are at risk to be placed precipitously into the cold sea and sustain the
physiological insults imposed by accidental immersion. Local cold injury is less a threat to deck
and shore station crews who must work outside in very cold weather or under conditions of a
high windchill index. They are usually prepared and adequately clothed to resist the deleterious
effects of exposure to cold air.
Immersion in cold water is different from exposure to cold air because of two physical
( 'I properties of water :
1. The thermal conductivity of water is approximately 26 times greater than that of air.
Therefore, during immersion, heat is conducted away from the body at 26 times the rate
it would be in air.
2. Water has a specific heat approximately 1,000 times that of air. Therefore, each cubic
centimeter of water in contact with the skin can extract and hold 1,000 times more heat
from the body than a comparable volume of air for any given increase in temperature.
The rate of heat loss from the immersed body is, therefore, a function of the temperature
differential between the skin £ind the water itninediiitely adjaeent to it and |he rate of heat
transfer from the body core to the sMn.
E^ologj^. The niogt important factors in determining the ra«6 of onset aftd depth
of l3ie hypothermia are water temperature and duration of immersion. In 1946,
Molnar, in his classical paper, emphasized the relationship between survival times and water
temperatures below SQ^^F (15°C). Immersion in water at 28 to 35°F (^2.2 to +1.7**C) may
result in unconsciousness in five to seven minutes and in death in ten to twenty minutes,
tlte iitt^Qimd htnd becomes useless in one t6 fke minutes dUe to loss of tactile sengtttttt.
Figure 21-5 illustrates the effect of variations in water tthaperatufe on tiie rate o#-fil Wf
body temperature.
21-11
"038
U.S. Naval Fli^t Surgeon's Manual
J I ■ , I I , - ■ ■ J 1 I
0 20 40 60 80 100 T20
MINUTES
Figure 21-5. Rectal temperature in an experimental subject after
swimming in water at various temperatures. Time 0 indicates water
entry; ^ indicates water exit (Golden, 1974).
Ajnother factor influencing the rate of onset of hypothermia is the amount of water
movement relative to the surface of the immersed body. Currents, turbulence, and body
movement each cause the water molecules next to the body airface to be exchanged more
frequently, thereby promoting increased heat loss due to conduction/convection. In water
at41*'F (5°C) for twelve minutes, it has been found that moderate work doubled the rate at
which rectal temperature fell because of increased blood circulation. Working as hard as possible
only shghtly decreased flie Kite of temperature loss at this temperature. Collis (1976)
deteitiiined that survival time could be increased by about one-third by holding still in the water
instead of swimming. Infrared thermograms taken of individuals who bia4 renpin^ neatly
motionless while immersed demonstrated the areas of greatest heat loss to be the inguinal and
thoracoaxUlary areas. CoUis developed a position called HELP (heat escape lessening posture)
21-12
Thermal Stresses and Injuries
for survivors in the water by themselves in which the knees are drawn up to the chest and the
arms are clasped together at the chest. Survival time in 50° F (10° C) water proved to be four
hours, or double the survival time of a swimmer in the same temperature water. Another
significant finding from the series of 5000 immemons in water with temperatures ramging
from 39° F (4°C) to 59° F (15°C) was that the drownproofing technique of flotation resulted in
a cooling rate 50 percent faster than that observed in subjects treading water with the head
above tl),e, surface.
A faetor which may inflwente tile rate of oMifct of hypothermia is the presence of body fat.
Keatinge (I960) described a linear relationship between fall in rectal temperature mi the
reciprocal of the mean skinfold thickness in men. It might be expected then that, all other
factors being equal, females, who tend to have a higher total percentage of body fat than males
of similar height and weight, should have a slower cooling rate on immersion than males of
similar height and weight. Golden and Hervey (1972) demonstrated that this is not the case
(Table 21-1) and that the overall rate of cooling of unclQthtd Individuals depends on a complex
interplay of many factors, notably heat production, body size, and fat insulation. ^
Table 21-1
Percentage Skin Fold Thickness and Mean Rates of Cooling
of Mixed Male and Female Subjects Immersed in Water at 9°C
% Fat
Mean cooling
Subject
Sex
(skin fold
Subject
rate
thickness)
''C/hour
Wendy
F
30
Andrew
10.7
Christine
F
20
Christine
9.1
Brenda
F
18
Brenda
5.6
Stewart
M
17
Tim
5.1
Ian
M
16
Will
4.4
Tim
M
14
Stewart
4.0
Will
M
14
Ian
3.1
Andrew
M
9
Wendy
2.3
(Golden & Hervey, 1972, published by permission of Cambridge University Press.)
The importance of protective clothing as a factor in the etiology of hypothermia has
been demonstrated experimentally by many investigators and is confirmed by aceouiuts of
21-13
U^. Naval Flight Surgeon*s Manual
survivors. The mechanism of protection at its most basic level, and with only a single layer of
clothing, is to reduce the rate of exchange of the water molecules immediately adjacent to the
skin.
^fsi^e^ of Immersion Hypothermia. In an excellent review Article, Golden (1974)
summarizes the physiologic changes seen as a result of nnmersion hypothermia. A precise
understanding of the physiological changes in man is hampered by lack of hard data. The
majority of the literature describes either the results of experimentally induced, relatively mild
states of hypothermia or ajiesthetic hypothermia in which shivering was abolished and
respiration controlled. With the exception of the Dachau work, most case studies relate
instances of hypothermia which had a relatively long duration of onset. Nevertfieless, the
understanding of physiological mechanisms in man has been extended by cautious extrs^lation
from experimental findings in animals.
Metabolism. Immediately following cold water immersion, the body attempts to maintain
its thermal integrity, but the rate of heat loss exceeds even the most violent efforts of the body
to increase metabolic heat production through exercise. Involuntary shivering reaches a
maximum at a core temperature of 95°F (35°C), but it declines thereafter to be replaced by a
rigidity of muscles during the range of 91.4 to 86** F (33 to 30''C), which, in turn, is abolished
around 80.6*' F (27° C). An extrapolation from animal data would indicate that the relationship
of oxygen consumption and body temperature is ahnost linear, and in dogs, oxygen
consumption jrt 20° C was only 15 percent of noimal. Since oxygen consumption in man is
laigely dependent on the shivering response, aE evidence suggests that the increase in metabolic
rate with cooling does not increase below a core temperature of 95°F (35° C).
The hyperglycemia resulting from hypothermia was first described by Claude Bernard. It
was also observed in the Dachau experiments in which it was found that the blood sugar level
was a mirror image of the rectal temperature. In the presence of shivering, blood glucose levels
rise if there is an ample supply of carbohydrates. But as metabolism declines with decreasing
body temperature, glucose utilization diminishes, and the early hyperglycemia continues. Where
there is no shivering during cooling, such as in anesthesia, the blood glucose level is maintained
or decreased. Therefore, in an individual whose hypothermic state was rapidly induced (acute),
hypei^ycemia should be observed, while in those individuals who developed hypothermia
slowly (chronic) or while expending energy at high rates (subacute), the blood sugar level should
be normal or subnormal. At temperatures below 86°r (30°C), glucose is metabolized slowly if
at all, and insulin's effect on glucose transport across the cell membrane is significantly
impaired. There is an immediate significant increase of free fatty acids in response to cold
exposure which is still demonstrable ei^t hours after expoaire. This attests that lipids rather
than glucose are the preferred source of energy in hypothermia.
21-14
Hernial Stresses and Injuries
Respiratory System. Hyperventilation with respiratory rates of 60 to 70 per minute is seen
as a result of the initial shock of entry into the cold water. There is a marked reduction in end
tidal PCO2, but it gradually returns to a httle above the original level. This initial
hyperventilation results in a reduction of arterial CO2 which causes a dramatic rise in pH, but as
Mbdd tenttp^fatuie fells, CO2 solubiHty increases and the arterid pH f alts. During rewarming,
this neido^, which is due in part to a metabolic component, may intensify, and the pH may fall
as low as 7.1. The shift to the left of the oxygen dissociation curve resulting from the decrease
in temperature is counteracted in part by a shift to the right due to lowering of pH. Respiration
becomes progressively depressed as the hypothermia deepens, and at near lethal core
temperatures, it is extremely di^ficnIt to detect.
CktrdtoVascubBT System. The cause of death in hypothermia is alnaost always cardiac in
origin. There is m initial stimulatory phase during which cardiac rate increases dramatically and
central venous pressure rises. During this period, a marked peripheral vasoconstriction occurs.
As the hypothermic condition deepens, cardiac rate decreases due to a direct effect of cold on
the pacemaker, and cia^ac output decreases as a-cHrect Gonsequenee. ©MMtioii of systole
increases, and the refractory period of the atrioventricular bundle is increased.
Arrhythmias are common in hypothermia. Extrasystoles are commonly seen on cold water
entry. Atrial fibrillation appears to be more a feature of acute hypothermia and has been
described in Dachau victims, World War II immersion survivors, in surgical patients with induced
hypothermia, and even in an In^sh Ghaimel swimmer. Atrisl iWiriUttiOja usually 0CC3|rs at a
body temperature of n°F (33°C). As temperature falls to 82.4 to 77°F (28 to 2S°C), there is
a dlaip increase in the incidence of ventricular arrhytirmias, ectopic beats, anid disgpiiation,
and if the heart is mechanically stimulated at these temperatures, development of venfricular
fibrillation is hkely to occur.
In humans, death due to cardiac arrest appears to occur between T8.# and 75.2**F (26 to
24PC); however, there are documented cases of apcidential hypothermia victims survivii]^ core
temperatures of 64.4°F (18°C). The nature of the terminal cardiac arrest has not been precisely
described. Extrapolations from animal experiments would suggest that when the heart is not
mechanically stimulated, arrest is due to simple asystoli, but when irritation occurs, ventricular
fibrillation is the cause of death.
Other Cardiovascular physiological changes indude an increase in stroke VQluine but a
reduction in cardiac output due to Ihe slowing to rate/Cenfeal venous pressuf^ iiicreases; blood
pressure falls, and there is a progressive reduction in total peripheral resistaw^e at temperatures
below 86° F (30*'C). Although coronary blood flow is reduced, it is sufficient for the needs of
21-15
U.S. Naval Flight Surgeofl's Manual
the hypothermic myocardium. Peripherally, the initial cold-induced vasoconstriction may be
replaced by cold-induced vasodilation on immersion in water below (lO'^C). This is
thought to be due to a direct effect of the cold on the smooth muscles of the vessels.
Electrocardiographic findings consist characteristically of bradycardia and increased
conduction time with concomitant prolongation of the P R, QRS, and Q-T intervals, and S-T
aevia1ion6 both upwards and downwards with a flattening or inversion of the T-wave. In
profound p^es of hypothermia, there is £iIso development of a "J -wave" (Osborne wave), which
is a poative deflection at the junction of the QRS and S-T s^ent. Figure 21-6 shows a typical
J-wave in an electrocardiogram of a 6 -year-old girl treated by Golden (1974) for hypothermia
with a rectal temperature of 76.3°F (24.6^C).
Figure 21-6. ECG (Lead II) trace taken from 6-year-old female with a rectal temperature of 24.6°C
(Golden, 1974).
A marked increase in blood viscosity with a sludging of red cells is also seen. Platelets
markedly decrease and clotting time is prolonged.
Kidneys. A marked cold diuresis occurs in the early stages of hypothermia as a result of the
increased central venous pressure and its depressant effect on the secretion of antidiuretic
hornaone. As jlie hypothermia progresses and blood pressure falls, the glomerular filtration rate
is jredfed. But, due to impairment of flie tubular transport mechanism, a higher percentage of
the filtrate is excreted, carrying with it a proportionate amount of the electrolytes which are
21-16
Thermal Stresses and Injuries
normally interchanged in this region. There is some evidence of lipoid accumulation in the distal
tubules due to exposure to the cold, and renal failure is a frequent complication of chronic
hypothennia.
Central Nervous System. As brain temperature falls, cerebral activity becomes impaired.
Amnesia is reported to occur at temperatures below 93.2^F (34'^C). When core temperature
falls below 91.4°F (33*^C), the individual becomes semiconscious, and introversion and apathy
are seen. Consciousness generally seems to be lost or severely impaired at rectal temperatures
of 87.8 to 84,2**F (31 to 29°C). Electroencephalogram changes appear as the body temperature
falls between 96.8 and 89.6°F (36 to 32**C). These dimges consist of decrease in amplitude of
the potentials in the occipital areas first, followed later by changes in the parietal and frontal
areas. At about Q6'^¥ (30*^0), large delta waves appear in the frontal area; the electrical activity
then declines until between 68 and64.4°F (20 to 18°C) when no potentials can be recorded.
As temperature continues to fall, muscle reflex activity becomes increasingly more difficult to
elicit. The pupils begin to dilate at about a coA temperature of 91.4°r (33" C) and are usually
fuUy dilated and unresponsive to light when the core tfflnperature has fallen to 86°F (30° C).
"After Drop. " Nearly all immersion hypothermia victims experience a deterioration in their
condition manifested by an "after drop" or paradoxical fall in their core temperature once they
have been removed from the cold water. This phenomenon has been described by many
investigators and is attributed to a continuation or progression of the rate of <3ia|^ of body
temperature for an additional 10 to 20 minutes after removal from the water. It is thon^t to be
caused by retuining cooled blood to the core from the reviving peripheral circulation. In the
Dachau experiments, the after drop averaged 1.9°C but did reach 4°C. Coincidental with the
after drop in temperature, there is likely to be a fall in pH and some degree of hypotension. But
in hypothermia due to immersion, there is usually insufficient time for renal compensation of
the abnormal fluid and electrolyte changes which take place. Even tiiough a grossly abnormal
physiological condition may exist, it is primarily a thermal disturbance, and it is lltat thermal
disturbance which must be promptly treated.
Diagnosis. Untreated accidental hypothermia carries an extremely high mortality rate.
Hypothermia should be considered in the differential diagnosis of all drowning victims as well as
in the less circumstantially obvious cases of uneonsciousness due to dcohol or drug intoxication
and trauma. The diagnolfe m®r feartf he confiBned by use of a spedd low-reading thermometer
or thermocouple. In the absence of a ajjeeial thermometer, a reasonably accurate assessment of
the core temperature may be estimated from the clinical signs and symptoms whose
physiological basis has been described in the preceding section. These signs and symptoms and
their relationship to body temperature are depicted in Figure 21-7 (Golden, 1973).
21-17
SYMPTOMS MB SMNS IN ilCVTE HYPOTHERMIA
Figure 21-7- TI^ crave KfttBseiits the behavior of body temp^tiare during cold watw iwrntoskjn wilh associated signs
^d sprmptomB encGimtered at various body temperatures (Golden, 1973, reproduced by Hnd pmnissioii of Ae Editor of
the Proceedings of fte Royal Society of Medicine).
Thennal Stresses and Injuries
The usual signs of "clinical death" are extremely unreUable in victims of hypothermia.
Below 80.6°F(27^C), all evidence of hfe is extremely difficult to detect. At these temperatures,
there is an intense bradycardia and respiratory depression coupled with hypotension and
extensive peripheral vasoftonslriction, all tending to make it difficult to palpate a peripheral
pulse or hear a heart beat. Muscles are extremely flaccid and the pupils are widely dilated. Even
cardiac standstill demonstrated electrocardiographically is insufficient evidence of death since
the hterature contains documented cases of cardiac arrest of durations up to one hour in
hypothermic victims who were subsequently revived. 'HierefMB, it is imperative that
r^stiscitaifive efforts begin at once.
Treatmmt. The goal of therapy is to restore to normal the core temperatute of accidental
hypothermic victims as expeditiously and safely as possible. The treatment of immersion
hypothermia may be divided into preventive, first-aid, and definitive segments. The most
effective treatment is undoubtedly prevention, and the issuance of proteeive Nothing and
personal survival gear to dtcrew members together with ihgKufitidns in flieSf proper ude teay
well reduce the incidence of unaaersion hypoflieniua cases. In spite of these precautions,
personnel aboard ship may be swept over the side, or adequately clothed and outfitted, downed
crewmembers may exceed designed time limitations for clothing protection in cold water, and,
once rescued, treatment may be required.
Treatment wSU depend on the c4iii^tions under which the rescue was ekecftted #1^* iife
tomecBate facilities ftvaffl^le. SurW&re who are rational and possess motor function, although
ijflVfeiing dramatically, usually do not require treatment beyond safeguarding against further
heat loss. If facilities are available for rewarming, they should be utilized. But, if the survivor is
well insulated and protected from further heat loss, metabolic heat produced by his own
shivering will rewarm him in time. Hot, sweet drinks, rest, and aVoidMtec of ttfi bteAetfted
environment are teconlitteflded.
The following paragraphs discuss itie treatmettt of the semioonscious, unconscious, or
t^parently dead victim.
First-aid Treatment. The primary goals of first-aid treatment are to prevent further lolS
heat and to maintain life until ^e surnvor can be traiispcfrted to a detttitiV^ fi-eatttient cenfiir.
H the distance to 1*6 travde^ requires more Ikan 20 to 30 minutes, attempte should be made to
provide definitive treatment on the spot.
1. Immediately remove the victim from the hypotiiermia-inducing environment.
2. Handle the patient gently in order to minimize the likelihood of development of
ventricular fibrillation in the sensitized myocardium. Do not attempt closed-chest
2M9
U.S. Naval Flt^t Surgeon's Manual
cardiac resuscitation. Do not attempt to undress the patient because the manipulative
efforts required to remove the wet clothing may be detrimental. In mild cases, wet
clothing' kna^ be removed and replaced with dry GldtJieS'drMaifikets.
Bi. MAtaiw a clear airway. The patient should be placed in a slightly head-down position to
combat hypotension. Semiconscious patients should' be tfansported in the same manner
in anticipation of unconsciousness which may develop as a result of the "after drop."
4. Further heat loss should be prevented by wrapping the patient in blankets, enclosing the
body in a large polyethylene bag, and insulating him from the ground. No attempt
should be made at ibis time to rewarm the patient actively by using hot water bottles,
catalytic warmers, or any other means.
5. Administer oxygen by oronasal mask.
The risk of developing ventricular ^dilation in the coId-seAsitibed myocardium must be
emphasized. Rrofound hypotherraia mimics cardiac arrest, and attempts to restore cardiac
activity by closed-chest cardiac resuscitation are likely to produce ventricular fibrillation.
Furthermore, should the heart be in arrest, any effort to restore normal rhythm is unlikely to
succeed until the myocardium begins to rewarm, when a spontaneous reversion to normal
rhythm may occur.
Defb0ive Treatment. Restoration of core temperature to normal levels may be
accompUshed by using either of two approaches, broadly categorized as external or internal. In
the external method, the surface is rewarmed in advance of the core, and heat is transferred
from the sheU to the inner body by direct conduction and by convection of the circulating
blood. External rewarming may be an active process in which heat is applied to the body by
iinmepioi^;i8,lp4°F (-d^^G) yfalt^i^ heating pads, hot water bottles, or heat cradles. Or, external
rew^mg may be .paasive in wid^ case no heat is appled to the patient Blankets may or may
not be used to cover the patient who is allowed to achieve, without active assistance, an
equilibrium state with ambient room temperature. In contrast to external rewarming, internal
rewarming refers to raising the core temperature in advance of the shell. Although case reports
are few in number, success has been reported by using such internal techniques as peritoneal
lavage with solutions warmed to 104°F (40°G), placing the patient on a heart-lung machine,
femoral artery bypass, and inhalation of warmed, water-saturated gases. Advantages cited for
the internal rewarming method of treatment are the rapidity with which normothermia can be
achieved, the more rapid return of cardiac output and the electrocardiogram toward normal,
and the avoidance of "rewarming shock" or further drop in core temperature during early
rewarming.
The melbod bif rewarming selected as fterj^y by the atteiiding Fli^t Sui^eon will depend
in part on facilities available, circumstances suiTounding Ibe immersion, condition of the
21^20
Thermal Stresses anA Injuries
patientj and the Flight Surgeon's familiarity with the various treatment modalities. In spite of
the promise inherent in the new internal rewarming therapeutic approaches, rapid, active
external rewarming probably remains the most successful and easily performed treatment for
the victim of immersion hypothennk. The following regimen is suggested for the diipboard
Flight Surgeon with the understanding that it may differ from that aaraiiable, or evai dedr^le,
in a Navy Regional Medical Center:
1. Handle the patient gently. If clothing must be removed, cut it off.
2. Rapidly rewarm the patient in a 106''F (41°C) water bath in whieh Hie ^ater is
agitated. A whirlpool bath is suitable for use aboard an attack carrier. For multiple cases
or where a whirlpool is not available, a small Ufe raft inflated near a source of hot water
is a satisfactory substitute. An unconscious, unclothed patient may be exposed ti^Wftfet
temperatures tip 'te ll2°F (44.5°G). Initially, the arms and lege should be kept out of
the bath to delay the revival of the circulation in the tissue mass of this portion of the
cold shell. This may reduce the work load on the cold myocardium and possibly reduce
the magnitude of the "after drop,"
3. Maintain H clear ailfway and administeE^S percent oxygen and 5 percent carbon djoxide
via an oronasal mask to overcome the o^ifgm debt that occurs on rewarming. If at all
possible, intub3|icj(i,§hould be avoided as it can produce ventricular fibrillation.
4. Closely monitor core tmapmmm, vital iigns, and electrocardiogram.
5. Start a central venous pressure monitor and draw blood for an immediate reading of pH,
PCO2, PO2, and electrolytes, and then follow these parameters as an indication of
- ' treatment progress. ' 1
6. Be prepared to' administer intravenous sodium biearbonate warmed to 98.4°F (37°G)
J before; transfusion. • • 1 ■
7. Do not give antiarrhythmic drugs since they have little value at lowered body
temperatures and may even precipitate ventricular fibrillation. Should ventricular
fibrillation develop, it should be remembered that defibrillation is of little value when
the cardiac temperature is below 82.4°F (28*' C). If on rewarming sinus rhythm has not
returned when deep body temperature reaches 86° F (30° C), then defibrillation should
be attempted.
8. Leave the patient in the hot bath until he is subjectively warm. Then remove him and
place him in a warmed bed. The patient should not be left in the hot bath until his
temperature returns to normal levels because there is a tendency for the temperature to
"overshoot" upon removal from the bath, and a subsequent difficulty in readjusting
may be encountered.
Recovery from acute hypothermia is usually dramatically swift following rapid rewarming.
Nevertheless, even after the patient revives, he should be treated as a total emergency and
constantly monitor^ until his temperature returns to normal and he is ambulattSiy.
Catastrophic arrhythmias have occasionally developed after it appears that acid base balance and
21-21
U.S. Naval Fli^t Surgeon's Manual
cardiovascular performance have returned to normal. The hypokalemia which is commonly
seen in hypothermia, despite the usually associated acidosis, is probably secondary to the
ij^lraceUular migration of |»otai8Uiin Mtid Aould not be interpreted as recpxiring yigorous
repljicfsment.
The most commonly seen, late comphcations of acute accidental immersion hypothermia
are pneumonia, renal failure, and pancreatitis.
Local Hypothermia
Local hypotherinic injury may be represented as a coQeiction of traumatic conditions whose
semily is chtaracterized by a continuum of tissue damage ranging from the most mild,
chilblains, to the most extensive, deep tissue freezing, Hie type of injury produced is a junction
of the temperature to which the body or its parts are e^ptjsed, the dHratioji of exposure, and
other concurrent environmental factors.
It is an accepted conwintion to divide injuries into *'freezing''i and "non-freezing" types.
Non-freezing cold injttrieis compAs ch&Mne and trench or immersidni foM. Chiltlattts insult
from intermittent exposure to temperatures above freezing acconipanied by hi^ humidity.'
Chilblain is the only cold injury which is not militarily significant.
Trench Foot. Trench foot and immersion foot are indistinguishable with respect to cause,
pathology, and treatment. Trench foot (immersion foot) results from prolonged exposure to
wet, cold foot gear or outtii^t immersion of the feet at temperatures uaiaUy below SO'^F
(lO'^C). At the upper range of temperatures, exposures of 12 hours or more will cause injury.
Shorter durations of exposure at or near 32°F (0°C) will cause the same injury. Dependency
and/or immobiUty of the feet aggravates and predisposes to the development of the condition.
Sailors fa sea"^*yasr or' soldiers and marines witii wet feet in trench, rice paddy, or foxhole
develop treialch foot.
Warm water immersion injuries were described during military operations in Vietnam
(Anderson, 1967). In these cases, the injury consisted of whitening and wrinkling of the skin
and pain in the feet after two days or more of water exposure. Additional exposure resulted in
erythema on the weight-bearing surfaces and edema. Complete recovery occurred following
proper foot care. In a seven to ten-day military operation in.wbi^ eontimious wet foot
exposure occurred, And^^n found that about 30 percent of the troops required evacuation for
immersion foot injury. This could have been prevented had the troops been able to dry their
feet for six to eight hours per day with boots and socks off, but such is rarely possible in
combat situations.
21-22
niemud Stresses and Injuries
Recently, Hawryluk (1977) described military operations in a temperate climate over a
13-day period when the minimum temperature ranged between 28 and 43° F- with a chill factor
betwecai 8 and 41**F. Cold injuries represented over one-third of the cases seen for treatment,
and approadmately one-third of these received diagnoses of ttench or immersion f<90t.
Frostbite. Frostbite results from the formation of miniscule crystals of ice within the
extracellular fluid of the skin and adjacent tissues and is caused by exposure to temperatures
below the freezing point. The severity and extent of injury are functions of the temperature and
the duration of eiqitwure. Figure 21-2 indicates that human flesh freezes at cooling values of
1,300 to 1,500 calories per squm-e meter per hour. With a wind velocity of 22 miles per hour,
exposure at temperatures of 17.6''F (-8°C) for one hour, or minus 22°F (-30°G) for one
minute, will cause human flesh to freeze. This graphic demonstration emphasizes the
importance of windchill as a causative agent in frostbite.
Pathogenesis. Tlie multiple and complex mechanisms eventually resulting in tissue damage
are not fully understood. Some of the mechanisms which have been implied are
1 . direct cold effect on certain cellular enzyme systems
2. intracellilliff hyperosmolarity secondary to cellular dehydration m tile water from within
the cell is drawn into tie ejcbracdlular fluid to replace the water in the extracelhiliF
space which has cjystalliaed into ice
3. mechanic^ disruption of the cellular membrane and intillpriBlw|a| gftuctures by ice
crystals, particularly during slow thawing during which some refreezing of the melt
occurs. The new ice crystals are actually larger than those formed during the original
freezing.
4. tissue hypoxia as a result of deeteased perfusion due to irreversible damage to capillaries
and smaD. vessels.
Diasntms. The development of frostbite is particulai'ly insidious, and the victim frequently
is unaware of its happening. Frostbite most commonly occurs on the face, hands, and feet. Its
onset is signaled by a sudden blanching of the skin of the nose, ear, or cheek. This may be
subjectively noted by the experienced as a momentary tingling or "ping-" Subjectively, the
patient feels that his face muscles will not work. TeUttlle, yellow-white spots appear earif, and
dieir early observation by another person may minimize tissue damage. A frozen extremity
appears white, yellow^hite, or mottled blue-white and is hard, cold, and insensitive to touch.
Even a very shallow or superficial frostbite injury may have the appearance of being frozen
completely solid because of the dermal freezing alone. An elegant classification of cold injury
by degree of severity is presented in NAVMED P-5052-29, but such designations are somewhat
21-23
U.S. Naval Flight Surgeon's Manual
academic in the clinical situation since the definitive classification into degree of injury is often
a *ffec08|[ipi^ve diagnosis and the treatment is the same.
Once thawing has transpired, the injured extremity usually bciConieS edematous. Large,
serum-filled blisters develop within an hour to several days after thawing is complete. Unless
accidentally ruptured, the blebs remain intact until the fourth to tenth day post injury when
resorption of the fluid begins. At this time, spontaneous rupture of the blebs may occur. As the
blebs diy, a har^ es©hat deydops on the injured surface. Within feree to four weeks, the eschar
begins to separate spontaneously, and the delicate healthy tissue beneath becomes visible.
Should the extent of the tissue damage be so severe as to preclude tissue healing, blebs do
not develop, and the skin remains cyanotic and cold. This is most commonly seen in distal
phalanges, and evidence of beginning mummification may be observed, often within a few days.
MurtmiKcation becomes more pronounced over a period of days, weeks, or months, and the
demarcation between healthy and dead tissue becomes more obvious. The viable tissues separate
and retract from the mummified until spontaneous amputation of the soft tissue is essentially
complete.
The foregoing description is based on a clinical pattern uncomplicated by infection or
premature surreal intervention. bifeStion or unwarranted early debridement may result in
exces#e tissue loss, osteomyelitis with need for successively higher amputations, extensive iddn
grafting, and prolonged hospitalization.
Treatment. Treatment of frostbite is directed towards the preservation of the maximum
amount of viable tissue and the restoration of maximum function. These goals are achieved by
r^i adherence to the following principles: gentieness in handUng the frozen parts to prevent
additional mechanical trauma, rapid thawing of the frostbitten tissue, prevention of infection,
early institution of active motion of the injured part, and avdidani^ of premature surreal
intervention. Mills (1973, 1976) has reported good anatomical and functional results by using
such a regimen of treatment.
Wben the patient is at a distance from a medical facility capable of providing definitive care,
the management of a frostbitten extremity is dependent on flie amount of time necessary to
reacb tiiat facility. If the time is only several hours, it is best that the frozen part be kept in the
frozen state until arrival. The patient should be transported with the extremity carefully padded
or sphnted to avoid mechanical trauma, and the affected part should be either isolated from tiie
heater of the transport vehicle or even placed on ice. Because there appears to be a direct
relationship between tite amount of time that tissue is frozen and the amount of residual tissue
21-24
Thermal Stresses and Injuries
damage, the frozen extremity of a patient who is more than several hours away from definitive
care should be thawed by rapid rewarming in an envirorunent where refreezing cannot possibly
occur. Then, the thawed extremity must be protected from pressure or mechanical injury.
Thawing of a frostbitten fsaet sfeould not be und^sdten whenever there is any danger of
refreezing; the danger of thawing and subsequent refeeezin| U greitter than the danger of
remaining frozen.
Upon arrival of the patient, the Flight Surgeon should perform a tiiorough phyiteai
examination to rule out generld hypothermia, concomitant injuries, and cardiorespiratory
problems. Should general hypothermia be present, or diould there be generalized or local tissue
anoxia secondary to blood loss or trauma, he must be prepared to perform intubation, cardiac
defibrillation, or other resuscitative procedures which may be indicated. Once the examination
and any emergency procedures have been completed, the affected part should be rapidly
thawed. A whirlpool hath at 100 to 108**F (38 to 42?G) n fee method of choice. Wiis
temperature range is warm enou^to dissolve the ice in tiKe tiiSwe raf idly , but not so warm
tissue damage might result from excessive heat. The part should be gently handled to prevent
mechanical trauma. Although the thawing process is relatively quick, it is usually cpiile painful,
and morphine or meperidine may be required for relief of pain.
As tissue thawing proceeds, a superficial pink flushing will be seen to progress distally along
the extremity. Immersion in the whirlpool bath should be continued until the distal tip of the
thawed part flushes, is warm to the touch, and remains flushed when removed from the bath.
Occasionally, the flush may not be pink, but rather burgundy or purple, colors which are
usually indicative of ischemia and retention of venous Mood, In frpstbite, hoi^ever, Jfte Clip
change seems to be cUrectiy related to ttie bath water temperature. The color change ill USUlilf
transient, but persistent cyanosis or ischemia, despite rapid thawii^^ may indicate increasing
pressure within the fascial compartment due to an associated fracture, sprain, soft tissue injury,
or disease, and a fasciotomy may be necessary.
With rapid thawing, the change is dramatic and the patient quickly becomes res^onfflve littd
even alert. So rjqjid, however, is this method of thawhig, that the rapid entry into the
circulation of liberated acid end products of metaboUsm may precipitate metabolic acidosis and
subsequent death as a result of ventricular fibrillation within one to three hours. Consequently,
initial care must also be directed toward the avoidance of acidosis. Electrolytes, pH, PCO2 , and
PO2 should be serially monitored m fluids and sodium bicarbonate are admhustered.
Electrocardiographic monitoring should be simultaneously performed.
Sensation often returns to the affected part with rapid thawing, but this is a transitory
phenomenon. The sensation disappears once the blebs develop and separate the epidermis from
21-25
U.S. Naval Flight Surgeon's Manual
the dermis or the dermis from underlying tissue. Sensation does not fully return again until
h&^x%>m complete.
Once thawing is complete, the injury is treated in an "open" fashion, and a modified
isolation technique is employed. If the lower hmbs were frozen, the patient is placed on
absolute bed rest, and the legs are elevated and kept on sterile sheets. A protective cradle
covered with sterile drapes is placed over the legs to prevent injury or pressure, and sterile
emm ple^ets are put between the toes. When the injury is to the hands and forearms, they
may be comfortably positioned on sterile sheets placed on the patient's chest and abdomen.
Attendants should wear clean gowns and masks, and when changing Unens or manipulating the
injured part, they should wear sterile gloves. Extreme care should be exercised to prevent
further injury during nursing procedures requiring manipulation of the affected part.
The primary goals during this phase of therapy are to maintam joint motion and prevent
infection. At the core of the treatment regunen is use of the wMrlpool bath at least twice daily.
The water temperature is maintained at 95 to 98.6° F (35 to 37°C), and hexachlorophene is
added to the water for its bacteriostatic effect. The agitated water of the whirlpool bath
cleanses gently and promotes physiological debridement while aiding circulation. This treatment
is extremely effective in minimizing infection, and as a result, antibiotics are seldom necessary
untesi there is a very deep mfection. A tetanus toxoid booster i& routinely administered.
Active exercises are the other indispensable part of this phase of treatment, and they are
begun as soon as possible. Hourly digital movements are demanded of the patient. Most patients
find the movement easier to perform while in the whirlpool bath due to the softening of the
hard eschar by the warm water. When there is lower extremity involvement, Buerger's exercises
are jp^drlhed f dr 20 to 30 minutes at least four times daily as follows:
1. Patient supine, legs elevated at 30° angle for two minutes
2. Patient sits on edge of bed, feet danghng
a. Flexes and extends ankle
b. Rotates lower leg
0. Spreads and closes toes
Slowly and deliberately for
three minutes
3. Patient hes flat m bed with le^ under blanket for five minutes
4. Repeat above cycle three to six times per session.
Tlie importance of active physiotherapy during the first six weeks for the prevention of flexion
contractures and joint ankylosis cannot be overemphasized.
21-26
Thermal StreBses and Itijuries
Because of the prolonged nature of treatment and the danger of addiction, narcotics are
used for control of pain oidy during the initial thawing process. After rapid rewarming, the
patient should be switched to Aspirin, Propoxyphene, or diazepam for the long recovery period.
Use of tobacco is prohibited because of the vasoconstrictive effect. Alcohol is generally not
permitted because of its variable effect on peripheral blood flow.
The blebs which appear shortly after the initial rewarming process should be left intact. The
fluid contained in the blebs is usually sterile, as is the underlying tissue. The blebs generally
rupture on about the third to seventh day, and as they dry, hard, dark, and often
circumferential eschajrs develop which may inhibit motion of digits, particularly the
interphalangeal and metacarpal phalangeal joints. Should this occur, the eschars should be
carefully split along the dorsum or lateral borders to avoid injury of the underlying
neurovascular bundles. The eschar should not be removed. The whirlpool bath will perform i&ia
fimction at a physiologic rate and minimize scarring which could occur from cutting into
granulating membranes during sui^cal debridement.
Generally by the 10th to 14th day, and almost always by the 21st day, the eschar has begun
to sluff into the whirlpool bath and healing is readily apparent. At that point, isolation
technique and sterile precautions may be terminated. However, the physiotherapy and
whirlpool should be continued.
De^itB adbemnce to the foregoing treatment regimen, some digits or distal portions of an
extremity may remain black and cold and appear nonviable- Surgical intervention should be
withheld until spontaneous amputation of the soft tissue is nearly complete. This may require
from three weeks to four months. At that time, the mummified portion may be surgically
removed without danger of retraction of distal tissue or a higher amputation than necessary.
Tfe i-ationale underlying tins phase of therapy is to permit the injured part every opportunity to
demonstrate ite viability. The physician must resist the urge to do something surgical as well as
the exhortations of the depressed patient to amputate the injured part prematurely and rid him
of the black foot or finger.
The single exception to this pobcy of nonintervention is when a thawed extremity wMch
was ^ozen for a relatively long period exhibits a dinicd pifetare dlniliir to anterior tibial
compartment syndrome. This includes pain, severe edema, restricted joint motion, evidence of
ischemia, and a marked increase in compartment pressures which is obviously compromising the
blood supply. In these patients, a fasciotoray and/or a sympathectomy should be considered.
The vascular response is almost immediate following a fasciotomy, and a sympathectomy,
according to Mills (1976), appears to promote a much more rapid resolution of iao^ irfeqiBfln
21-27
U.S. Naval Fli^t Surgeon's Manual
which may be present, as well as rapid diminution of edema and a significant lessening of pain.
It has also been observed that the combination of the two procedures seems to hasten the
demarcation between healthy and nonviable tissue in the affected part.
The whole therapeutic approach for deep freezing injuries is by necessity lengthy, aaad it
requires a great deal of cme and psAience. During the first several months, pleasant environment,
frequent visits, encouragement, and occupational therapy are mandatory. The patient should be
involved in his own treatment by explanations of tissue changes that are taking place and
discussions regarding his progress. The patient's observations of joint motility in the whirlpool
slioula be reinforced by the physician in order to substantiate that, despite the grim appearance
of the injury, function is being preserved. Asm my figaie-destroying illness, a hi^ cidoric, hi^
protein diet with vitamin supplements is beneficial.
Other modalities of therapy have been proposed from time to time, and still others are
under investigation. The beneficial effects ascribed to steroids and antihistamines in the
treatment of cold injury have not been clinicsdly demonstrated. The u^ of vasodUators hais been
disappointing. In studies of mierocipcilktion of experimental animals followibig 'fireezing and
lhawing, Mundth (1964) reported that immediately following thawing the circulation was
apparently unimpaired, but within a few minutes, evidence of obstruction could be seen in the
venules. The obstruction apparently began with aggregations of platelets, followed by piling up
of erythrocytes behind them with stasis extending back through the capillary bed to the
skt^oles. Wifllin Wo hours or less, tfie stasis had become irreversible, tod the vessels were
totally filled with a structureless, hyaline-like material. There was tissue edema evidettGe of
extravasation of hemoglobin into the perivascular spaces. Mundth (1964) investigated the use of
low molecular weight Dextran in rabbits following freezing and thawing. Examination of the
microcirculation demonstrated that the low molecular weight Dextran had alleviated the
post-thawing obstruction and was effective in reducing tissue loss in frozen rabbit feet if it was
infiised as late as two hours following thawing. Clinical eXperiencfc with, ftm meSthbd of
treatment is stiU Umited.
Hyperthermia
When heat production and/or exchange of heat from the environment to the body exceeds
heat loss, a state of hyperthermia may develop. Circumstances in which the potential exists for
the development of hyperthermic conditions are ubiquitous. Some examples are personnel
inspections during hot and humid weather, recruit training, Marine field maneuvers in tropical
tor Mhtr0|iioal chm^tes, strenuous physical activity by in^viduals wi^ sunburn, duties in ^ps'
tn^ieering spaces, the "greenhouse" effect in poorly ventilated and unairconditioned aircraft,
and extravehicular activity (EVA) by astronauts, hi his roles as industrial medical officer and
21-28
Thennal Stresaes and Injuries
( ^
general medical officer, the Flight Surgeon is frRquently involved not only in the treatment of
such cases, but also in the assessment of environmental risks, evaluation of equipment, and
training of personnel.
Fhysiolc^ of Hypei^enaia
In a discussion of the interaction of environmental physical parameters and physiological
processes, it is customary to adopt the engineering usage of the terms "stress" and "strain,''
particularly since the body's final physiological state reflects both the independent and
integrated results of all those factors which exert an influence on heat exchange and the body's
regulatory mechanisms. The term "stress" denotes the force or load acting upon the biological
system, and the term "strain" is used to designate any resulting distortion of the biological
system. Conventionally, stress factors are heat, cold, humidity, radiation, air movement, and
surface temperature. Thermal strain, as a response to the imposed thermal stress, may manifest
itself in specific cardiovascular, thermoregulatory, respiratory, renal, endocrine, etc. reactions
which differ in type or degree from accepted norms. A thermal stress is categorized as
acceptable when man is able to compensate without undue strain, but it is CQjiMdered
macceptabk when man is able to compensate but inrnm severe strain, m when He is unable to
compensate «id incurs ©xcesive jtrsdn. Hiermalstrmms are mt&gom&A as those interfering with
work performance and safety, and those with more overt manifestations of physiologic
t ^ decpmpensation, such as heat rash, heat cramps, heat exhaustion, heat stroke, or cold injuries.
Table 21-2 contains frequently encountered symbols used to designate environmental and
phyeitdt^oal v^liaWes in heat exchai^ and then- definitions. The interaction between man and
a heat str^ emitonment can be represented by the empirical Heat Balance Equation:
M±R±C-E=S
where
M = metabolic rate or heat production of man
R = radiative heat gain to or loss from man
C = eonvec^e and conductive heat gain to or loss from man
E = evaporative cooling
S = heat storage in man.
Radiation, eonthietioiEi, convection, and vaporization of watrr as methods of heat exchange have
been discussed in an earlier section of this chapter. In a state of tliermal <^quilibrium, the
equation ma^ be rewritten as:
M±R±C-E = 0.
)
21-29
U.S. Naval Fli^t Siugeoa's Alanual
Table 21-2
Symbols and Definitions for Physical Factors in the Thermal Environinent
and Physiological Factors in Heat Exchange
Physical Factore
Physiological Factors
Symbol
Meaning
Symbol
Meaning
To Air temperature using dry bulb ther-
mometer,
Tr Mean temperature oj surrounding sur-
faces (wall temperature). In presence of
radiant heat, Tr > Ta.
V Air velocity {fptn or m/s).
T, Temperature of the 6" black globe. Tg
exceeds T„ when T,- > T,,. Elevation of Tg
in equilibrium with radiant heat varies in-
versely with convective cooling by V. With
appropriate coefficients T^represente R+C.
Pwn ■ Water vapor pressure of ambient air.
Tw„ Temperature of the wet bulb thermom-
eter. Evaporative cooling under forced con-
vection depresses reading of T„i, below T„,
the degree varying inversely with in
air fully saturated with water vapor (100%
Tet Effective Temperature Scale. An em-
pirical index combining T„ (or T^), T»i„
and V into a single value based on sensory
effect.*
°Cet Elective Temperature in degrees Centi-
grade.
Mean skin timpefafure.
Tc "Core" or central temperature (mea-
sured in the rectum, esophagus, or near the
tympanic membrane.
P„, Water vapor pressure of wetted skin at
skin temperature.
A Total surface area of the body {m-^.
s Area of wetted surface.
— X 100= %of wetted body surface.
A
M Metabolic rate of body heat production
(kcal/hr).
met Unit of M per m-/ hr.
Resting M = 1 met or 50 kcal/m'' hr
VO. max Maximum oxygen uptake. Also called
maximum aerobic work capacity.
SR Sweat rate {kg/ hr).
E Body heat loss by evaporation (kcal/hr) .
BF, Blood flow to the skin (I/m- min).
_ M/A [kcal/m- hr per
C Conductance - j _^ degree of gradient]
•ET Scales in the form of nomograms (Basic Scale for men stripped to the waist and Normal Scale for men lightly
clothed) were derived from tests on men moving between two climate chambeia, a test chamber wrth T», T,,„ aiul
V fixed in various combinations, and a reference chamber with stUI air fully ratitrated held at temperatures rang-
ing in different tests from 0 to 43*C- AU combinations of T„ T,„, and V producmg immediate thermal sensations
which were equivalent to those experienced in the reference chamber were assiwied the same Effective Tempera-
ture, namely that of saturated still air at that temperature.
{Minaid, 1973).
Heat transfer by radiation (R) and by convection and conduction (C) between man and Ids
environrnfflit may result in a positive or n^ative heat balance. IVmp example, if the environment
is cooler than the man, a negative (toward the environment) heat balance will result. Conversely,
when the environment is warmer than the subject, a positive heat balance (toward the subject)
results. If uncompensated, this latter state results in excessive heat storage and leads to the
various clinical hyperthermic conditions. Table 21-3 illustrates how the Heat Balance Equation
applies to three different circumstances of temperature and vapor pressure gradients between
skin and environment. It should be noted that when Tg<Tg and P^^ approaches or equals P^g,
ecpiiUbiium is not possible either at rest or during work.
21-30
Thermal Stresses and Injaries
Table 21-3
Heat Balance Under Different External Temperature Gradients
and Factors Limiting Eindurance Time for Work
External Heat Ejrfufance Tftne R«OTMentttive
Gradient Example Balance Limited by. Enviro nments
Temperate climate.
Also flinmally mmal woifc
places.
Tropical climate. Also
canning, textiles, laundries,
deep metal mines.
Hot desert climate. Also
manufacturing of primary
metals, glass, chemicals, etc.
Thermoregulation. Ajfljoui^ the thermQiegulatory mechanisms in man have not been fully
explicated, animal experiments have provided convincing evidence that the tempmtee
regulating e«aiter in man lies in the hypothalamus. The attfierioE poftijQtt'i^pears to contain the
"heat loss" center which responds to increases in its own temperature as well as to afferent
nerve impulses from receptors in the skin. The center mediates heat loss through increased
blood flow to the skin and sweating (man) or panting (other mammals). Minard (1973), in his
excellent discussion of the physiology of heat stress, proposes a iratiiiilel fot #1© 0l«flfl<tregulatory
^5tem controlling body temperature under conditions of heat stress. He structii*«8^#.in0iid^lfr
an analog of an en^eeting System known as a n^ative feedback proportiiMlal conWaBtes-
Feedback is negative because the error signal is the difference between the input, the set point
of the thermostat (BT-O^C for the hypothalamus and 34.0°C for the skin), and the output, T^
and/or Tg. It is a proportional controller because the central drive and effector responses
(BFg and SR) are proportional to the error signal. In the absence ctf a heat loadyceffi&ititeNe is
zero, output and input being equal. The model predicts that when equilibriutti is reached under
a ghren heat load, core temperature and mean skin tempiafatoUf* ^OW^ilt of the system) will
stabilize at a level above the set point by an amount also proportional to the load. The deviation
from the set point is called the "load error," and the effectiveness of the controller in
temperature regulation depends on its sensitivity to the error signal, or gain. The gain factor is
high in individuals with high heat tolerance, and it increases in acclimatization.
Sweat Rate. In response to the stimulus of a heat load resulting in an error signal, skin sweat
glands are activated. The number of glands recruited and the rate of secretion of each gland
determine the total sweat rate. The estimated 2.5milhon «©erine glands csm secwrtS Sweai at
peak rat«s ©f more than 3 kg/hr. for up to an hour in higMy acclimatized men^ and ^ey can
maintain rates of 1 to 1 .5 kg/hr. for several hours. When there are no restrictions to evaporation
T. >Tb Tg=2S°C M = R+C+E Work Rate
P,»>>P«
7^ = X Tj = 35 "C M = E Work rate and elevated P,
Pw, > Pw. and/or low "V
(Restrict evaporation)
T '^Tg Tg=4S°C M+R+C=E Work rate and maximum
p1 > * P». capacity to sweat
(Free evaporation)
<mM*d, 197^.
21-31
U.S. Naval Flight Surgeon's Manual
of sweat from the skin, i.e., SR = E, and under steady state conditions of work and heat
exposure, evaporative coohng is regulated to balance the heat load (M + R + C) up to the
maximum rate of sweating of 1 kg/hr. Under steady state eonditions, of work, is constant
despite ambient temperatures widely varying from cool to moderately hot, and any elevation of
Tg above 37**G depends solely on M, the metabobc work rate. Under constant ambient
conditions, however, SR varies with M, to which the elevation of is proportional. Thus, the
central drive for sweating is determined by work rate, M, but the actual sweat output is
modulated by skin temperature to meet evaporative requirements under conditions from cool to
hot, up to the limits of the Stveating mechanism!.
Sweat Evtpomtion. As stated previously, the heat of vaporization of Sweat is 0.58 kilo-
calories. The efficiency of body coohng by sweat is a function of the rate of evaporization. The
rate is determined by the gradient between vapor pressure of wetted skin, P^g, and ambient air,
P^a, multiplied by a root function of air velocity at the skin surface, V^ ^^ and s, the fraction
of body surface. A, tfeat is wetted. When evaporation of sweat is resbicted by a redut^d vapor
pressure gradient due to high ambient humidity, more sweat glands are recruited in order to
increase the area of wetted body surface. K the ev^orative Cfinohng is sufficient to balance the
heat load under these conditions, core temperature remains essentially unchanged. As P^^
increases or V decreases, s approaches A, and when s = A, the body surface is 100 percent
wetted. Any further increase in sweat production does not contribute to cooling, and the sweat
Mpi off the body and is wasted. Any ferflidr restrieti&ift on ©results in body heat being stored
tociseasid vahies for both % aoA Tf.. The-fiiermal center responds with an increased central
drive for sweating. But, as rises, P^^ and tbe evaporative rate increase also, so that W new
steady state may be estabUshed but at a cost of increased tbermoregulatory strain, as reflected
in further evaluation of SR, BFg, and HR (circulatory strain).
Htsar^fetey s^ifeat rate under conditions of fea© evaporation varies line^y^ with heat load and
is pitipdirtiOadl to M + R + C. Under conditions of restricted evaporation, howeveri when s/A
approaches one, SR is greater than E and is proportioiial to the increase in and The sweat
rate tends to dechne with time of heat exposure, particularly under restricted evaporation and
when the skin is extensively wetted, but the decline does not interfere with heat loss as long as
SR>E. The dechne might be regarded as an adaptive mechanism to conserve body water and
electrolytes under conditions in which more sweat is produced iban is useful.
Cardiovascular System. Under comfortable ambient conditions, Tg is normally 33 to 34°C,
but under heat stress, it may approach to within a degree or two of T^, or it may decline to as
milok: as> ICt to 15°C below in the cold. Changes in core to surface gradient are accompanied
hyMW^^m-M the rate of blood flowing from the core to the surface to meet changing needs
in heat conductance. Heat conductance is defined as units of heat transferred to the
21-32
Thermal Stresses and In|imes
environment through the skin per unit time per degree of temperature gradient. Under
conditions of heat stress, Tg rises and the core to skin gradient narrows. Consequently, a greater
volume of blood must flow through the skin each minute to achieve the same rate of heat
exchange as in a neutral environment. This is the basic cause for heat strain on the
cardiovascular system. Conductance, which is a niefiil inde!k of the strain, is expressed by the
foUowing equation:
C =
M/A
(kcal/m^/hr. per degree of gradient).
The narrower the gradient for a given M, or the higher the M for a given gradient, the greater is
the BFg recpiired to transfer metabolic heat from the ctW^e to t^e envirorirHtnfl
In a thermally neutral environment, Tg is lower during work than at rest because of
redistribution of blood from the skin blood vessels to those of active muscles. The return of
adequate venous blood to the heart is maintained by the reduced capacity and increased
r^istance of skin and visceral vessels togetiier witik the pumping action of the muscles. This
facilitates increased car dl*c olltpnt Which is proportional to the percentage of maximum oxygen
uptake (percent VO2) required by skeletal muscle work. When there are f^sternil heat loads
concurrent with the performed work, however, both the central drive for increased conductance
and the rise in local skin temperature cause dilation of skin vessels, thereby increasing their
blood capacity and reducir^ their resistance. BFg increases but at the cost of reducing venous
return to the heart, resulting in a smaller stroke Volume, In 6tdet to tiaeet^e oxygen demand of
the working muscles, cardiac output can be maintained only by further constriction of
^^lanchnic vessels and an increase in heart rate. Thus, the thermoregulatory need for increased
BFg, as estimated by C, increaass from a quarter of a liter per minute at rest in a neutral
environment to over two Uters per minute in men working at three to four met (unit of M per
m^/hr.) under heat stress.
Core Temperature. Figure 21-8 schematically presents selected thermoregulatory responses
to heat stress. In Zone A (Full Compensation), SR and BFg increase proportionally with the
total heat load (M + R + C). is maintained at a uniform level which is determined only by M
and which is independent of ambient temperatures at lower levels of external heat stress. This is
termed the "prescriptive zone" to indicate the range of thermal environments in which men can
work without strain on homeostatic core temperature. The upper Umit of the prescriptive zone
21-33
U.S, Naval Flight Surgeon's Manual
in highly accUmatized men working at 300 kcal/hr. is 31 to 32*'Ce'j'. The upper limits of this
zone are lower at high work rates because is higher.
Zone A Zone B Zone C
25 S7 2« 31 59 — \ »
Effective Temperflture(*C} Increasing- Hcot Stress
Figure 21-8. Thermoregulatory responses to heat stress in Zone A (Full/Compensation),
.B(Time Limited Compensation),\ and G (Uncompensated Heat Storage). Graph illustrates
the effector responses (SR, BFg), circijatorjr strain (HR), and the controlled variables
(Sq, in a bi^y acdimatijsed man working at one-third VO2 max (M'^^SOO kcal/hr.) at
ler^ of heiiit stress up to his limits of tolerance. Responses under steady state conditions
aie Uaear -wMi Effective Temperature in Zones A and B. In Zone C, tiie steady state is
itttpoBe^te. Dadhed lines indicate continuous heat storage and show trends only of T^jTg
!SR; and HR with increasing heat stress (IVSnard, 1973),
T(. in a man performing steady work at 300 kcal/hr. is higher in Zone B (Time Limited
CompemAtipn) than in the prescriptive zone up to a T^ limiting value of 39^C (102.2°F). This
represents the hi^est core temperature at which a MgMjr acclimatized man can maintain a
steady state of thermal balance, and then for only two hours or less. The upward slope of T^ in
Zone B indicates an attempt to maintain the core to surface gradient as Tg reaches higher levels,
although there is a thermoregulatory strain imposed on T^,.
1^ maximum tolerable level of heat stoess eorresponding to the T^ limit of 39°C (102.2°F)
has been determined to be 34 to 35°Cet. Men who ate less fit or less wdl-acdiinatized for
work at 300 kcal/hr. would reach limiting levels for tihermal baltmce at lower core temperatures
21-34
.Thermal Stresseg and InjurieB
and at corresponding lower levels of external heat stress. As a practical guide, the average core
temperature of men should not exceed 38°C (100.4°F) for a work shift.
The border between Zones B and C marks the upper limit of man's capacity to sweat. Thus,
in Zone C, rates of heat loss fail to match rate of heat gain, and heat storage ensues with T(.
and Tg rising continuously in proporiion to the heat load. Rate of storage may be accelerated by
fatigue or failure of the sweating mechanism. It is not possible to achieve a steady state during
continued work, and this is indicated by broken lines in Zone C (Uncompensated Heat Storage).
Under extreme heat, e.g., 40 to 45*'Cets the core to surface gradient will be reversed, and the
blood returning from the skin will heat the core rather than cool it. MetaboUc processes are
accelerated by the rising core temperature, further increasing the rate of bod^jT tfJliperature rise.
Without cessation of work and removal from the environment, continued exposure in Zone C
inevitably leads to collapse from circulatory failure or heat stroke.
Under intense radiant heat loads, skin temperature rises rapidly to the pain threshold (45''C,
113**!'), jmd it n ifee pidn which becomes the limiting factor in toleranee time rather than heat
storage ift defelJer tissues.
Heat Tolerance
AccUmdtixtitiott. Any wdl motiyated young man in good physical condition who works for
the first time under conditions of heat stress will exhibit signs of heat strain evidenced by
increased heart rate, high body temperature, and other signs of heat intolerance. But on each
succeeding day of heat exposure, his ability to work improves and signs of strain and discomfort
diminish, hi other words, he adapts to the thermal stress, and as a result of his Working m a hot
enviroimient, he has acquired and etihitticed tolerance to ettvironjnental heat stress called heat
acchmatization.
The acclimatization process begins with the first exposure to heat and is achieved most
safely and expeditiously over a period of one to two weeks by progressive degrees of heat
exposure and physical exertion. In order to acMeve MiaximUin acehmatization, tbe work level
should be in the 20D to 300 keal/hr. range. Sedentary work levefc will not resiilt in adaptation.
A factor S5>parently essential in inducing acclimatization is the sustained elevation of T,. and Tg
above levels for the same work in cool envirorunent. Acclimatization ordinarily cannot occur
when heat stress levels exceed a certain level, and personnel working in areas of unusual stress,
such as firerooms and enginerooms, should not be expected to adapt physiologically to their
envirormient if the parameters outlined in Table 21-4 are exceeded.
2135
U.S. Maval Flight Surgeon's Manual
Table 21-4
Bureau of Medicine and Surgery Recommended Heat Stress
Design Conditions for Firerooms of Surface Vessels*
Parameters
Lower Work Level
Inside Space
Upper Work Level
Inside Space
Dry-Bull) TeniptTature (°F)
Wel-Bulb Temp. rature (°F)
Globe Temperature (T)
KflVclivf Air Velocity At
Man (fpm)
Relativ'e Humidity (%)
Aittibient Vapor Rressttte (aiiitt Hg)
Wet-Bulb Globe Temperature
Index ("F)
Mean Radiant Temperature (°F)
97
83
117
105
84
125
250
56
25:3
250
42
24.6
91.2
155.4
94.3
162.0
*A11 of the above figures apply to normal work sites 1yi& a time-wei^ted-mean metabolic tmtB of 76
kcal/(in^'br) for the upper work level and 96 kcal/m2-hr) for the lower work level; data were based upon no
cunndative fat%ue in peisonnel (NAVMED P-5010.3, 1974).
Once acclimatization has occurred, there is a significant increase in sweat output which is
[.iroduced at a lower Tg in comparison to both sweat rates and skin temperatures early in the
adaptive process. Within the environmental restrictioiis discussed above, Ute mcrease in
v!vaporativ€ cooling with a steeper core to skin gradient is sutfieient to contpensate fully for the
tteat load. This is demonstrated by restoration of the core temperature to levels observed while
(^if.fforming the same work in a cool environment. Although BFg remains elevated following
a:;climatization, the circulatory load is diminished as evidenced by a reduction in heart rate.
, Acclimatization to wet heat increases tolerance to dry heat and vice versa. ITie reason why
'olerance to wet heat is increased is not clear, n&i jire the underlying changes in the
thermoregulatory axis which cont ol the adaptive process itself. It h well known that men viho
work at hot industrial tasks acquire levels of acclimatization commensurate with their average
heat exposure, but increased work demands or increased environmental stress may overload
their thermoregulatory capacity and lead to signs of overstrain. Heat accKnialization retjuires
|ti- liodic reinforcement, such as occurs daily during the work week, A partial loss 6t
iy liniatization may be demonstrated after return to work following the weekend, and should
ll. ' ah^cnce be longer, such as a vacation of several weeks, the loss of acclimatization may be
substantial.
21-36
Thermal Stresses and InjurieB
A summary of physiological indices of advanced heat acclimatization is provided in
Table 21-5.
Table 21-5
Physiological Indices of Advanced Heat Acclimatization
Piapressive Adaptive Response
1. Cardiac Output (estimate
1. Increased on day one; decreasing toward nonnal vnik progresaiye ex^
by noninvasive indirect
pogiire, .|
technique)
2. CJardiovascuUtr Reserve
2. Gradually increasing hom fiidt day of expogare.
(measured in terais of
peripheral resistance
with peripheral vascular
collapse theoretic end-
point)
3, Body Temperatures
3. Markedly increased on day one; graduid noimalizing thereafter.
(rectal, deep esophageal,
After adaptation to tropical environmental temperatufes a thermal
tympioik, akin)
equilibrium was achieved within 30 minutes in acclimatized sub-
jects doing constant moderate work.
4, Sweat Rate
4. Low on day one, increasing daily thereafter until day 8-10, after
which torn if a^in de^teffi^id W^iEWd nontfal.
5. Urine OsmokMty
S. Sii^t increase On day bite with iflttf* rapid increments Uii^r^Mler
until day 810. Osmolality then decreases each day towSEfd nor-
mal (response is simitar to that of sweat rate).
6. Serum Osmolality
6. Studies are thus far incomplete, but suggest that changes are
latateid during aedbnatization. Investigation gngg^sfB lliiEil^
atb^r adaptations tend to maintain the osmolar integrity of the
serum,
(NAVMED P^OlO-3, 1974).
Physical Fitness. A state of good physical fitness alone does not confer heat acclimatization,
but physical training &fen wilJiout heat exposure does improve heat tolerance, ais in^Of t^d by
somewhat lower heart rates and core temperatures in men exposed to heat dFler conditioning as
compared with before conditioning. However, sweat rates do not increase and skin temperature
remains high. Therefore, it may be said that physical conditioning enhances heat tolerance by
increasing the functional capacity of the cardiovascular system. This results from an increase in
the number of capillary blood vessels in muscle, thus providing larger interface between
circulating blood and muscle for exchange of oxygen md metabolie waste products. Small veins
in tissues other than muscle also develop increased tom and are able to reduce their capacity
during exercise, thus promoting an increase in pressure in the large central veins retoming blood
21-37
U.S. Naval Fli^t Surgeon's Manual
to the heart. Together, these factors allow an increased maximum oxygen uptfdce in the
physically conditioned individual, permitting him to withstand a greater circulatory strain of
work under heat stress,
Surface Area to Weight Ratio. Heat loss is a function of body surface area, A, and heat
production is a function of body weight, Wt. Therefore, a low A/Wt ratio is a handicap for
jbdiViduals perfotHritig MStahied work tinda' conditions of thermal stress. In obese individuals,
as well as those with compact or stocky builds* the A/Wt ration is relatively low. If lacking in
accUmatization, physically unfit and obese men are at greater risk of succumbing to heat stroke.
Age and Disease. A healthy worker over 45 years of age may perform well on hot jobs when
he is allowed to work at his ovm pace. However, under demands for sustained work output in
the heat, he is at a physiological disadvantage compared to the younger worker. Between
ages 30 and 65, the maximum oxygen uptake declines 20 to 30 percent, and the older worker
has less cardiovascular reserve capacity. In addition, at levels of heat stress above the prescriptive
zone, the older worker compensates less effectively for the heat loads, as demonstrated by his
higher core temperature and peripheral blood flow for the same work output. This has been
attributed to a delay in onset of sweating as well as to a lower rate of sweating, contributing to
greater heat storage and a longer recovery time. The presence of any degenerative diseases of the
heart and blood Vfm^h intensifies the age effect by limiting the circulatory capacity to transport
heat from the core to the surface.
Illness other than degenerative disease may predispose to the development of heat injury
under rifild environmental condition which would ordinarily not be considered to represent a
^niKcant risk. Bartley (1977) lists the following heat factors which have been reported in the
literature as significant risks for development of heat stroke: acute febrile illness, fatigue, recent
immunizations with subsequent reactions, acute and convalescent infections, medications, past
history of heat injury, chronic disease such as diabetes or cardiovascular disease, following
certain surgical procedures, and lesions of the hypothalamus, brainstem, and cervical part of the
gpiftM cordi
Water and Salt Balance. Successful adaptation to heat and the maintenance of effective
work performance are dependent on the replenishment of the body water and salt lost in sweat.
Sweat volume may amount to 12 liters in a 24-hour period (Dasler, 1971), leading to a
contracted extiacellular fluid space. A fully acclimatized worker weighing 70 kg can secrete
lo' elpit kilograJms of sweat per eight-hour shift. Failure to replace water lost in sweat,
dy^iti continued sweating, may result in severe dehydration due to loss of intracellular as well
as extracellular fluid. Although water deficits of one kilogram (1.4 percent of body weight of
21-38
Thermal Stcesses and Injuries
standard man) can be tolerated without serious effect, deficits of 1.5 kg or more during work in
the heat deplete circulating blood volume. Even an acclimatized man will exhibit signs and
symptoms of increasing heat strain (elevated and HR, thirst and severe heat discomfort)
regemblii^ tiiose seen in an unacclimatized individual. With water ddftrfts'>of tvr& W four
Mlograms (three to six percent of body wei^t), work performance is impiired, and continued
work will lead to signs of incipient heat exhaustion.
A factor in the development of acclimatization is the successful attempt by the body to
conserve salt. Already hypotonic sweat is produced in increased quantities with an even lower
salt content, and the rate of renal iSodium (Na+) leabsorption is itocieised. Among the
meehnni&ms proposed to explain the ability to retain Na+ is an increased plasma renin actl^cl^
concomitant with the incremented aldosterone secretion which occurs during aceUmatization.
Recent studies (Francesconi, Maher, Bynum, & Mason, 1977) using small numbers of
experimental subjects suggest that heat acclimatization may reduce the increase in plasma
potassium (K+) induced by mild exercise at high ambient temperatures. No significant
differences wca?e observed in urinary potas^m excreted by eiiffleirfi^ and sedentary subjects.
No significant difference^ ia jplasiiia Na+ levels were devaonatrnted betvfeen a)i@rjQlstiig.iUi!d
sedentary men, but there was a significant reduction in urinary Na+ excretion in the exerciiN^
men.
The estimated average diet of the general population of the United States contains about
15 gms/day of sodium chloride, including salt shaker supplementation at fhe table. This woidd
meet the needs of an acclimatized worker producing six to ei^tt Mlo^ams @f ^i^u'eat contaimng
one to two grams of salt during a mgle ^ift During Ike perii^d of aediitist^ation, #%«#lier
with no previous heat exposure might require supplemental salt because, although maximal
sweat rates in unacclimatized workers are lower (four to six kilograms per shift), salt
concentrations are higher (three to five grams per kilogram of sweat) than after acclimatization.
Despite the difficulty of trying to equate time spent in physical conditioning, drills, or field
exercises v«th shifts, a similar magnitude of loss may be. experienced by jnUitary personnel. A
salt defieit of 15 to 25 grams may occur during the ffest several days of increased thermal stress.
If field rations are consumed as meals, supplemental salt is not required because each ration,
including the accompanying salt packet, contains 31 grams of salt, and daily dietary intake; of
salt may reach 93 grams.
An individual's greatest need for salt would occur during the glmultancoHs stresses of initial
physical conditioning and heat acclimatization in a hot, humid envfeonmmt wi#iout water
restriction. Although salt tablets, which are 10 grains (0.648 gms) each (0.255 gms of sodium
and 0.393 gms of chloride), are available, both experimental and dinical data suggest that
21-39
U.S. Naval Fli^t Sui^eon's Manual
unrestricted use of supplementary sodium chloride or salt tablets is contraindicated under most
conditions of heat stress. CostiU, Cote, Miller, MUler, and Wynder (1975) found minimal
physiological benefit in supplementing drinking water with electrolytes when sufficient
qiiantili^ of tiiose ions were available in the daily diet, and subjects were permitted to ingest
food and drink ad tibitum. A physiological plasma sodium chloride level can be achieved by
providing adequate water, a normal diet, and a salt shaker on the table for conservative use, with
no more than the equivalent of two grams of aipplementary salt (preferably not as salt tablets)
per day.
Pr<^res8tve dehydration may occur if water is replaced without concurrent replacement of
salt because homeostatic controls are designed to maintain a balance between the electrolyte
concentrations of the extracellular and intracellular fluid compartments. Deficient salt intake
with continued intake of water tends to cause hypo-osmolality of the plasma which suppresses
pituitary antiduretic hormone (ADH). The renal tubules then fail to reabsorb water, and dilute
urine containing Uttle salt is excreted. Thus, electrolyte concentration of the body fluids is
hdmeostatically maintained but at the cost of depleting body water and ensuing dehydration.
Under continued heat stress, symptoms of heat exhaustion develop similar to those resulting
from water restriction but with more severe signs of circulatory inefficiency and notably little
thirst.
BUMEDINST 6260.2 series provides current statements on salt and water requirements.
Alcohol. Many authors have reported an excessive intake of alcohol by patients within hours
or a day or two prior to onset of heat stroke. Striking reductions in workers' heat tolerance on
the day following alcoholic excesses have been described. Suppression of ADH by alcohol has
been described, and the loss of body water in the urine and resultant dehydration have been
postulated to be a primary mechanism.
Hypertherttiie Bbieas
T3ie €la8ii:Bcation of hyperthermic illness used in tJds chapter is the one agreed upon jointly
by committees representing the United Kingdom and United States in 1964. A summary of tiie
etiology, signs and symptoms, treatment, and prevention of heat illness is presented in
Table 21-6.
Heat Stroke. Heat stroke is a bona fide medical emergency, and if treatment is not instituted
iromediStely, the mortality rate is high. It occurs when the thea-moregulatory mechanisms fail
for reasons as yet undetermined. The central drive for sweating becomes inoperative, and
cooling by evaporation is lost. There is an uncontrolled accelerating rise in T,. due to
2140
Table 21.6
Qasafication, Medical Aspects, and Prevention of Heat Dlness
Category
Piedfapcisiiig Faclors
UiKterlying Physiological
Disturbanw
TtCMmeni
Prevention
1, Temperatun Regulation
Htai Stroke Heal Stroke: 1) Hfil dry dUii: red, mottled or
and cyanotic. 2) HfgfcaiM/rainf T,.40.5'C and over.
Hea Mgfei^yrtsOa jj Brain disorders: mental confusion, loss of
consciousness, convulsions, coma as continues
to rise. Fatal if treatment delayed. Heat Hyper-
pyrexia: milder form. lower; less severe brain
disorders, some sweating.
1 ) Sustained exertion in
heat by unacdimatized
workers. 2 ) Lack of phys-
ical fitness and obesity.
3 ) Recent alcohol intake.
4) Dehydration. 5) Indi-
vidual susceptibility. 6 )
Chronic cardiovascular
diseaie in Uw dderly.
Heal Stroke: Failare of
the central drive for
sweating (cause un-
known ) leading to loss of
evaporative cooling and
an uncontrolled accelerat-
ing rise in T^.
Heat Hyperpyrexia;
Facial ratter fltan com-
ftete fiiiiure of ' ^wttMjng.
2. Circulatory Hypostasis
Hfot Syncope Fating white
in heat.
3. Salt and/or Water Depletion
Heal Jlroite: Immedi-
ate and iiipid cooling by
immersion in chilled wa-
ter with maisage or by
wrapping in wet sheet
with vigorous fanning
with cool dry air. Avoid
overcooling. Treat shock
if present. Heat Hyper-
pyrexia: Less drastic cool-
ing required If sweating
stlUpnsoitaadT, < 40.S.
Medical screening of
workers. Selection based
on health and physical
fitness. Acclimatization
for 8<14 days by graded
work and heat exposure.
Monitoring workeif dur-
ing sustained work in se-
vem beat.
staiDdiu ere^ and immobile Lack^aedimalizatian.
Pooling of blood in di- Remove to Oiolt^ l
lated vessels of skin and Recovery pnMnpt
lower parts of body. complete.
a) Heat Exhaustion
b) Heat Cramps
4. Stin Eruptions
a) Heat Rasli
(miliaria rubra;
"'prickly heat")
b) Aaliidrotie Hem
Exiiaustion
(miUaria
pnriunda)
1) Fatigue, nausea, headache, giddiness. 2)
Skin clammy and moist. Complexion pate, muddy
or hectic flush. 3) May faint on standing with
rapid thready pulse and low blood pressure. 4)
Oral lemperature normal or low but rectal tem-
perature usually elevated (37.j-3K.5°C). Water
restriction type: Urine volume small, highly con-
centnitcd. mirietfm lypti Urate leu con-
centrated, chlorides less than 3 g/1.
Painful spaanu of muscles used during work
(arms, legs, or abdominal}. Onset during or
after wort horns.
Profuse tiny raised red vesiclea (blister-like)
on affected areas. Pricking sensations duiing heat
exposure.
Extensive^ areas of sUn which dg init; sweiit
on heat exposure, but present goose fie^ i^^ar-
ance, which subsides with cool environments. As-
sociated with incapacitation in heat
5. Behavioral Disorders
a) Heat Fatigue -
Transien t
b) Heat Fatigue
Chronic
Impaired performance of skilled sensorimotor,
mental, or vigilance tasks, in heat.
Reduced, performance capacity. Lowering of
self-imposed staadacds otsoiM behwrior (e.g.,
alcoholic overisdylgeawe). Inibiliiy to isoncen-
tiate, etc.
I ) Sustained exertion
in heal. 2) Lack of accli-
malizatioh. 3) Failure to
replace water and/or salt
io«t in swaat.
I ) Heavy sweating dur-
ing hot work. 2) Drink-
ing large volumes of wa-
ter without replacing saft
loss.
Unrelieved exposure 10
humid heat with skin con-
tinuously wet with un-
eviq^orated sweatt
Weeks or months of
constant exposure to cli-
matic heat with previous
history of extensive heat
ra^h and sunburn. B.aisty
seen except in troops in
wartime.
Performance decrement
greater in unacdimatized,
and uRskilied men.
Workers at risk come
from homes in temperate
climatef. Cor long resi-
dence in tropilal lati-
tudes.
I ) Dehydration from
deficiency of' water and/
or salt intake. 2) Deple-
tion of drculating blood
volume. 3) Circulatory
tsom competing
for blood flaw to
^ui mod to active mus-
cles.
Loss of body salt in
sweat. Water intake di-
lutes ekcirolyies. Water
enters muscles, causing
spasm.
Plugging of sweat
gland ducts with retention
of sweat and inflamma-
tory reaction.
Skin trauma (heat rash;
sunburn) causes sweat re-
tention deep in skin. Re-
duced evaporative cooling
cause; beat inloleraiit^.
Remove to cooler en-
vironment. Administer
salted fluids by mouth or
^ve I-V infusions of nor-
mal saline i.9% ) it un-
conscious or vomiting.
Keep at rest until urine
volume and salt cOBtsit
indicate that salt and «ra-
ter balances have been re-
stored.
Salted liquids by
mouth, er more moitwt
relief W I^V fatlinton.
Mild drying lotions.
Skin cleanliness to pre-
vent infection.
No effective treatment
available for anhtdrotic
areas of skin. Recovery
of sweating occurs grad-
ually on retum to cooler
dinutte.
Acclimatization. Inler-
miUant activity to attiH
venous retura to heart.
Acclimatize workers
using a breaking-in sched-
ule for I or 2 weeks.
Supplement dietary salt
only during acclimatiza-
tion. Ample drinking wa-
ter to be available at all
^am and to fa« Ue-
qMiyiliajfiB wttit di^.
Discomfort and physio-
logical strain.
Not indicated unless
accompanied by other
heat illness.
Psychosocial stresses Medical treatment for
probably as important as serious cases. Speedy re-
heat stress. May involve lief of symptoms on re-
Igrmonal imbateoce but turning home.
Adequate salt intake
with meals. In unacdi-
matized men, provide
sailed (0.1%) drinking
water.
Cooled sleeping qnar-
ten to allow skin to dry
between heat exposures.
Treat heat rash and
avoid further skin trau-
ma by stntl^uni. Eetio^
relief totii ttuilafiicd
beaL
AccLimatization and
training for work in the
heat
OrieittatiDn on life
abroad , (cuttoBM, cli-
mate, liniim eoiffitieat,
etc.)
(Leithead & Liiid, 1964, pubiyied by penuission of F.A. Davis Co.)
U.S. Naval FU^t Sutton's Manual
uncompensated heat storage. Predisposing factors include any of those which adversely atfect
tolerance to heat. Prodromal symptoms are headache, malaise, discomfort perceived as excessive
warmth, or even those symptoms associated with heat exhaustion. The onset is usually abrupt
ydih. gadd^ft loss of cotiscioumess, convulsions, or deliriixm^ Typically, sweating is absent, and
paEtient himaelf may have noted this prior to #f otmt of his other symptoms. Since the
patient may continue to ingest water in l||e^.' ^^§e of sweating, overhydration rather than
dehydration may occur. Should diuresis occur as a result of this, it should be interpreted as an
additional sign of the critical condition of the patient. During the early stages of heat stroke, the
patient may experience a febrile euphoria once sweating has ceased and has risen. Physical
signs are a fluished, hot, dry skin ; in severe eases,;^bere may be petechiae present secondary to
direcit tihertnal injury of va^ular endothelium wMch initi#es pidtelet a^egation. T,, is W^,
feeqweiiiy in excess of 105°F (40.5^C). A rectal temperature of 108^ F (42*'C) is not
uncommon. As continues to rise, loss of consciousness, convulsions, and coma may ensue.
The patient's pulse is fuU and rapid, wlule the systolic blood pressure may be normal or
elevated, and the diastohc pressure may readily become depressed. Respirations are rapid and
deep and simulate Kusiffliaiil biealhpig. As the pathBhi's condition worsens, peripheral vascular
collapse may occur manifestfd by a rapid ptise^ hypoteiBrfon, and cyanolis. BreatMng becomes
shallow and irregular. Pulmonary edema and renal failure may develop. If the patient survives
until the second day, recovery often occurs, but relapses may occur in the first few days after
the temperature has been reduced from the critical level.
Treateient ii directed toward rapid restoration of normal temperatijre. Imtaediate attempts
should be made to lower body temperature to safe levels, T(. of 100 to 101°F (37.5 to 38°C).
TTie longer hyperpyrexia continues, the greater is the threat to life. In the field, the patient's
clothes should be removed, and if there is a source of cool water nearby, he should be immersed
in it. Otherwise, water should be sprinkled over the patient and its evaporation hastened by
fanning. In addition to these coohng measures, attendants should rub the victim's extremities
and trunk briskly to Increase circulation to the skin. The patient should be transporlBd as ^on
as poissible to a f acilty properly equipped to perfoiffli definitive treatment, ©wring transporta-
tion, coohng efforts should be continued by permitting passage of air currents through the open
door of the field ambulance or helicopter. Once the patient reaches the hospital, he should be
placed immediately into a tub of water and ice. His extremities should be continuously
massaged as noted above. During immersion, his rectal temperature should be closely
monitored, and when it drops to between 100 and 101**F., ttie patient may be removed to a
hospital bed, Rectal temperature should continue to he monitored every ten minutes until
stable. During the first several days, the patient is susceptible to hypothermia as well as relapses
of hyperpyrexia. It is therefore desirable to maintain rectal temperature between 100
and 101*^F. Rapidly increasing temperatures can usually be managed with ice water sponge
21^2
'Thermal Stresses and liijuriee
baths and farmingi preisifiitciUs dW5p8 ifit teiiipfefatufe fflaf fe^ife jtidfeious use of warm
blankets. Shivering is s^ociated with increased involuntary muscular activity which is
undesirable because it accentuates tissue hypoxia and lactic acid acidosis. If simple warming
measures fad to control shivering, the physician may administer small intravenous doses of
diazepam (10 mg).
• Hypotensive shock usually responds to the cautious administration of balanced intfa^fiftiil
fluids, but plasma volume expanders may be useful if the patient is normoth^rmle. ¥a8Cipi*©§3(fi#
are to be avoided. Central venous pressure, serum electrolytes, and hourly urinary output must
be carefully monitored to avoid hyperhydration. Replacement fluids should be sufficient to
repair imbalance of serum electrolytes and to restore acid-base balance, but care must be
exercised to detect early signs of pulmonary congestion, rising venous pressure, or renal failure.
Administration of oxygen by face mask or nasal catheter be useful to combat ti^e aaojrf^
Caavulsions m,ay be contcoUed by intravenous use of diazep^un or ^ost-Wfting barbitlKr^ib^
(sodium pentothal). Long-acting barbiturates and narcotics are contraindicated.
Serious physiologic damage and altered response to heat stress may persist long after
recovery from heat stroke. There is evidence to suggest that heat stroke victims may be more
susceptible to re^WWt, ^episodes of heat illne^ under lp0.,.|jitenp jBa^ronitiiental Conditions,
"nterefoie, they should never be returned to heat slFegs; wkflar to that which precipitated
illness without an evaluation and appearance before an appropriate Medical Board. A "Heat
Casualty Report" (NAVMED 6500/1) should be submitted to Chief, Bureau of Medicine and
Surgery, Department of the Navy, Washington, D.C. 20372. . ,^
Heat ifyp&^yimiti. Heat hyperpyrexia is a milder f orin of the sfane illness in which there is
partial, rather thatt complete, failure of the central drive for sweating. In heat hyperpyrexia, the
core temperature is lower, less than 105°F (40.5° C), and some degree of sweating is present.
Central nervous symptoms and signs are less severe. Treatment is directed tow^ards lowering core
temperature as in heat stroke, but due to the less severe nature of the illness, less drastic
measures may be adequate.
Circubtaiy Hypostasis. Heat syncope is the clinical manifestation of circulatory hypostasis
and is an entity familiar to military medical persormel. It is most commonly seen in personnel
standing in parade formation in hot outdoor climates. It is unrelated to salt or water deficiency
or to excessive physical activity. Lack of acclimatization may be a predisposing factor together
with the enforced immobihty of standing in parade formation. The syncope results from a
pooUng of blood in dilated ves^ls of skin and lower parts of the body. Vagotonia may be a
contributing factor. The momentary cerebral ischemia is reheved promptly once the patient's
21-43
U.S. Naval Flight Sui^eon'e Manual
pQeture becomes horizontal as a result of the faint, and recovery is complete once the patient is
moved to a cooler area.
Salt and/or Water Depletion. Disorders of salt and/or water depletion include the clinical
entities of heat exhaustion and heat cramps. These conditions are most commonly seen in
unacclimatized personnel who have sweated profusely while performing heavy exertion under
conditions of thejmicd. stress. The sweating meekanism remains functional under adequate
central drive, hut the patients have mismanaged their water and salt replacement for that lost in
sweating.
1. Heat exhaustion. Patients with heat exhaustion suffer peripheral vascular collapse as a
result of dehydration and depletion of circulating blood volume. The depletion of the
circulatory blood volume may be absolute and secondary to failure to replace water and salt lost
in sweat, or relative due to circulatory strain from competing demmds for blood flow to ^an
and large skeletal muscles. The condition is characterized by profuse sweating, headache,
tingling sensation in the extremities, dyspnea, giddiness, palpitations, and gastrointestinal
symptoms of anorexia, nausea, or even vomiting. The patient may complain of neuromuscular
disturbances with trembling, weakness, and incoordination. He may also experience cerebral
signs ranging from slight clouding of the sensorium to actual loss of consciousness. Physical
examination reveals a patient in mild to severe circulatory collapse with a pale, moist, even
dammy skin and a rapid (120 to 200 beats per minute at rest), thready pulse. Systolic blood
pressure may be normal at the time of exaanination, bul prior to the onset of the Ubiess and
while at work, it may have been quite elevated (180 mm,Hg or hi^er) and then precipitously
fallen while work continued. The pulse pressure, however, generally remains decreased at the
time of examination. Oral temperature may be normal or only slightly elevated, but rectal
temperature usually is found to be elevated in tiie range of 100 to 102"F (37.S to 38.9°C). It
may be even hi^er defiending on the type and duration of physical jrctivity prior to the onset
of illness. In the water restriction type of illness^ urine volume is small and the urine is hi^y
concentrated. In the salt restriction type, urine is much less conoetiffated with the chloride level
being less than three grams per liter.
Patients with heat exhaustion generally respond rapidly once they have been removed to a
cool place and have rested. Their water deficit should be restored. If strenuous exertion
preceded onset of iUneiSg, Jtttd if examination of their urine indicates a salt deficiency, cautious
administration of 0.1 percent salt solution, orally, or physiologic saline, intravenously, may
accelerate recovery. Patients should remain at rest until urine volume and salt content indicate
that salt and water balances have been restored. Immediate return to duty is inadvisable except
m the mfldesl cages. A 24 to 48-hour period of limited duty for personnel recovering from an
episode of severe heat exhaustion is recommended.
2144
Themal Stresses and Injuries
2. Heat eromps. Heat cramps are painful spasms of muscljei^i^^ped teing worit^^^^^(^^
ab^omi^ail) wi^ dieir onset being observed during exertion or after work hours. They may
occur in conjunction with heat exhaustion, or they may occur as an isolated illness and with
normal body temperature. The patient has usually sweated heavily during hot work,
experienced thirst, and drunk copious quantities of water without replacing salt loss. The
patient presents with cool, moist skin, and his temperature is normd or only sli^tly elevated,
ffis muscular soreness must be differentiated from tiiat QC<aOTJlg in association rhabdomyolysis,
which is accompanied by muscle ByecifQ^ often resulting in tea-colored urine. Once the diagnosis
of heat cramps is confirmed by serum/urine chemistries, treatment consists of medication for
pain and restoration of the salt deficit by 0.1 percent salt solution, orally, or physiologic saline,
intravenously.
Skin Eruptions and Behavioral Disorders are summarized in Table 21-6.
The Flight Surgeon is encouraged to refer to NAVMED P-5052-5, "The Etiology,
Prevention, Diagnosis, and Treatment of Adverse Effects of Heat" and NAVMED P-5010-3,
Manual of Naval Preventive Medicine, Chapter 3: "Ventilation and Thermal Stress Ashore and
Afloat*' for a more detailed discussion of these topics.
Indices of Thermal Stress
In an effort to maintain maximum productivity of peiBonnel while mmamng their
likelihood of developing adverse reactions from exposure to thermal sttem, attempfe have been
made throughout the last several decades to integrate the several environmental, physiological,
and behavioral variables affecting heat transfer from man to the environment into a simple
index. Such attempts have not met with unqualified success. Such an index must take into
consideration dry bulb, globe, and wet bulb temperature readings as well as air velocities at both
ventilation duct opening and woife location. In addition, workers' body terap^aturesi T»di?k
16a&, heart rates, and pre- and piftgte*pogure body wei^ts must be considered. Ideally, the
resultant index ijrotild jssess tiig insdividual worker's cardiovascular reserve undet Cerent
degWies of heat ^tire^.
Chapter 3, "Ventilation and Thermal Stress Ashore and Afloat," in the Manual of Naval
Preventive Medicine" (NAVMED P-5010-3), concisely descrilbes various indices of tiiermal stress
atiA sOttiimim ih^ir advantages and disadvantages. The Wet Bulb Globe Teajperature Index
(WBGT) md tiife Physiolo^eal Heat Exposure Limits (PHEL) are the most widely used lherw«l
indices in the Navy.
21-45
U.S. Naval Fli^t Suigeon's Manual
Wit Globe Tettiji^^llti^
This index was dieveldped ih ^4 kte 19S0% to provide a eonvewieiit mefliod to assess,
quickly and with inltiiMttm operator skills, conditions which imposed intolerable levels of
thermal stress on military personnel. Fundamentally, the WBGT Index is an algebraic
approximation of the Effective Temperature concept.
The WBGT Index, is computed from readings of (1) a stationary wet bulb thettttometer
exposed to flie sun and to ttiepievailiiig wind, (2) a blacic globfe ^ermornk^ ^iititaily exposed,
and (3) a dry bulb th^mometer shielded from the direct rays of the sun. It is important that the
readings be taken in an area representative of the conditions to which the personnel will be
exposed. Construction and assembly details for a WBGT Index field apparatus can be found in
NAVMED P-5052-5. The temperature of the wet bulb is depressed compared to the dry bulb
reading for the air temperature because of evaporation resulting from the natural motion of
ambient air. Therefore, a principal adrantage in using the WBGT Index is that wind velocity
does not have to be measured.' Of the Six formulae which have beeii developed to obtain the
WBGT Index, only two are in common use:
WBGT Index = (0.7 x WB) + (0.2 x G) + (0.1 x DB)
WBGT Index = (0.7 x WB) + (0.3 x G)
where
WB =5 wet-bulb teiriperature
G = globe temperature
DB = dry -bulb temperature.
The first formula was originally applied to outdoor environments and the second to indoor
^'a@i8s' It has since befin demonstrated that the first formula is reliable in both situations,
litpndexuee of heM casualties has been reduced during Marine Corps recruit trainmgby^pply^
thei WMST Index, Table 21-7 ontUnes the reponnnmdations for diffetent levels of pJiyaiiKd
activities at several WBGT ranges. It appUes especially to personnel during training and
recreational exercises in hot weather. It is not a substitute for the PHEL curves (discussed
below) whose application is more suitable for an industrial type exposure, nor is it necessarily
useful in operational settings.
The development of a WBGT Meter, which is a compact electronic instrument that
independently measures the dry-bulb, wet-bulb, and globe temperatures and air velocity, and
translates these variables directly into the WBGT Index, has provided the Flight Surgeon with a
portable means to assess thermal stress in any space aboard ship.
21-46
Theimal Stresses and Injuries
Table 21-7
WBGT as a Guide in Regulating Intensity of Physical Exertion
During First 12 Training Weeks in Hot Weather*
WBGT
Index
cn
Intensity of Phydcal Exertion
78-81.9
Extremely intense physical exerlbii iiftay j!«e<%*
itate heat exhaustion or heat Stroke. tll^6USfC
caution should be taken.
82-84.9
Discretion required in planning heavy exercise
for unseasoned personnel This is a marginal
limit of emironmental heat stress.
85-87.9
Strenuous exercise and acthrity (le., close order
drill) should be ciartiiQled for new and un-
seasoned personnel during the first three weeks
of heat raposure.
88-89.9
Strenuous exercise curtailed for all personnel
with less than 12 weeks training in hot weather.
90 and
Above
Physical training and strenuous exerdse sus-
pended for all personnel (ocdi^es operational
commitmait not for training purposes).
*This table must hot be used in lieu of the Physiological Heat Exposure Limits
(PHEL) (NAVMED P-5010.3, 1974)
Physiological Heat Exposure Limits (PHEL)
Integration of human metabohc heat production with WBGT Index has allowed for the
refinement and redefinition of heat tolerance limits. These newer indices have been designated
PHEL. Hkt PHEL recognize that under conditions of maximum work and heat stress the heat
strain, although readily apparent, will be revea-dble. These curves rejpresent the results of Navy
research on personnel whose age ranged from 18 to 40 years. The end point designated as an
acceptable tolerance limit was a rectal temperature of 102°F {38.9°G) or a rapid rate of
temperature change. Time-weighted means were calculated for both metabolic heat production
and WBGT exposure in ordet to alldw fbt tite subsequent development of a set 6f tiitte
maximiini heat e^osure Hmlts. The experimental data ftdte W^ch the t*HEL derived
dlbwed for the detelopiifeftt of a related series of tM/wofk ftttioi far different degrees of
physical activity.
21-47
U.S. Naval Flight Surgeon's Manual
The Physiological Heat Exposure Limits are maximum allowable standards, and tiiey should
be applied only in cases of short-terra work exposures of up to eight-hours duration. The limits
presume that no prior heat injury is present and that no cumulative heat fatigue exists prior to
re-exposure. Whether or not these assumptions are vahd has not as yet been demonstrated.
In the appUeation of heat stress standards, sound health, physical conditioning for the
specific task, and adecpiate re^ and nutrition are essential in order to lakmme the effects of
heat stress. Drinking water should be unrestricted and readily available. Threshold WBGT values
for the hottest two-hour period of the work shift should be determined based on the workload
of personnel. Table 21-8 presents the WBGT threshold values useful in identifying heat stress
levels at which sound preventive measures should be instituted. They should not be confused
with PHEL which deal witih niaximum tme-weightetl-mesm limitations on an individual^iwork
capacity in hot environments.
Table 21-8
Recommended Threshold WBGT Values
for Instituting Sound Hot Weather Preventive Measures
Work IiQad
Threshold 2-Hour
Exposure WBGT
Values (°r)
Light Work
86
(time-weighted-mean metabolic rate
of 152kcal/hr)
Moderate Work
82
(time-weighted-mean metabolic rate
of 192 kcal/hr)
Heavy Work
77
(time-weighted-mean metabolic rate
of 232 kcal/hr)
(NAVMED P.5010-3, 1974).
Figure 21-9 illustrates a PHEL chart for praotical usage. Work levels corr^ponding to
curves A, B, and C are given in Table 21-9. TaHe 21-10 combines the data presented in
Figure 21-9 and Table 21-9 and describes Physiological Heat Exposure Limits as functions of
WBGT Index and metabolic work rate. When conditions of thermal stress preclude the worker's
completing an eight-hour shift, the PHEL for that particular WBGT Index is often referred to as
"stay tinie." Adherence to exposure tblie limits permits adjustment of the work/rest cycle in
21-48
Thennal Stresses and Injuries
order to allow the body to dissipate the heat stored during periods of activity. Cool rest areas
should be provided to maximize the benefits of the rest period and to avoid cumulative heat
fatigue. Environmental engineering can do much to modify the determinants of heat stresa, but
aboard diip, operational KK%encies and economic constraints lasy mandate l3Ei& use qf the
number and duration of exposures as the most practical stiA expedient measure for the
prevention of heat illness.
I 2 3 4 5 6
HRS NMRHI973
Figure 21-9. Physiologic heat exposure limit (PHEL) chart
for practical usage (NAVMED P-5010-3, 1974).
2149
U.S. Naval Flight Surgeon's Manual
Table 21-9
Duties Corresponding to Metabolic Rates of Re^jective PHEL Curves in Figure 21-9
PHEL Curves
(^wm i^ctsbolic Rates)
Duties*
"A"
(152 kcal/hr)
(192 kcal/hr)
"C"
(252 kcal/hr)
Water Level Checkman during other than heavy repair or Gafiualfy control
activity.
Bumerman during other than heavy repair or casualty control functions;
Messenger during other than full power conditions or when continuous
mobility is not required.
Messenger daring full power operation or other activities requiring continu-
ous mobility; any personnel involved in heavy repair work requiring man-
ual labor (e.g., pump disassembly); casualty control functions; laundiy/
scullery work assignments.
*These duties are comparable with thoee assignments found aboard steam propulsion plant ships rated at 600 and 1200
pounds per square inch.
(NAVMED P-5010-3, 1974).
Table 21-10
Physiological Heat Exposure Limits versus WBGT*
Curve "A"
Curve "B"
Curve
"C"
WBGT
{ty^jf. Metabolic
Rate =152 kcal/hr)
('■wm Metabolic
(*wm Metabolic
Rate = 252 kcal/hr)
Rate = 192 kcal/hr)
Hrs.
Mins.
Hrs.
Mins.
Hrs.
Mbs.
84
(Over 8 hrs.)
7
10
3
10
86
(Over 8 hrs.)
6
00
2
40
88
7
10
5
00
2
10
90
6
00
4
10
1
50
92
5
00
3
30
1
30
94
4
20
3
00
1
20
96
3
40
2
30
1
10 ■
98
3
10
2
10
1
00
100
2
40
1
50
0
50
102
2
20
1
40
0
40
104
2
00
1
20
0
40
106
1
40
1
10
0
30
108
1
30
1
00
0
30
110
1
20
0
50
0
20
112
1
10
0
50
0
20
114
1
00
0
40
0
20
116
0
50
0
40
0
20
118
0
50
0
30
0
10
120
0
40
0
30
0
10
122
0
40
0
20
0
10
124
0
30
0
20
0
10
* Assumes no cumulative fatigue or predisposing illness prioi to heat stress exposure.
(NAVMED P-5010-3, 1974).
21-50
■ Theitnal Stresses and Injuries
References
Anderson, G.T. Minutes of the 66th Joint Medical Research Conference. Washington, D.C.; Office of the
' Director of Defense Research and Engineering, 4 April 1967.
Hartley, JJ). Heat stroke: is total prevention possible? Military Medicine, 1977, 142, 528-535.
Bleckley, W.V. Temperature. In P.Webb (Ed,), Bioastromuties data book (NASA SP-3006). Washing-
ton, D.C.: U.S. Government Printing Office, 1964.
GoUis, M.L. Man in cold water. Navy Lifeline, January/February 1976.
Collie, M,L,, Stdnman, AJM,, & Chancy, S.D. Aceidental hypothermia: an experimental study of practical
tewarming methods. yltJiation, Space, and Environmental Medicine, 1977, 48, 625-632.
Gostill, D.L., Cote, R,, Miller, E,, Miller, T., & Wynder, S. Water and. electrolyte replacement during repeated
days of work in lite heat. Aviation, Space, and Environmental Me^icme , 1^75, 46,
Dasler, A,R., & Hfirdenburgh, E. Decreased sweat rate in heat accUmatization. Federation Proceedings, 1071,
30, 209.
Davis, T.R.A. Non-shivering thermogenesis. Federation Proceedings, 1963, 22, 777-782.
Department of the Navy, Bureau of Medicine and Surgery-. Cold injury (NAVMED P-5052-29). 1976.
Department of the Navy, Bureau of Medicine and Surgery. The etiology, prevention, diagnosis, and treatment of
adverse effects of heat ^AVMED P-50S2.5>. 1957.
Department of the Navy, Bureau of Medicine and Surgery. Manual of naval preventive niedicine.
Chapter 3: Ventilation and thermal stress ashore and alloat (NAVMED P-5010-3). 1974.
Department of the Navy, Bureau of Medicine and Suigery. Water and salt requirements in hot environments and
dija^a(BtJMEDINST 6260.2 series),
FrancesGoni, R., Maher, J., Bymmi,- G., & Mason, J. Recurrent heat exposure: effects on levels of plasma and
urinary sodium and potasMmga in resting and exercising men. Aviation, Space, and Environmental Medicine,
1977, 399-404.
Golden, F.S.C. Immersion hypothermia. In A. Borg & J.H, Veghte (Eds.), The physiology of cold weather
survival (AGARD-R-620). London: Technical Editing and Reproduction, Ltd., 1974. Pp. 77-90.
Gol4e|L, F.S.C. RecQgnitjon and treatment of immersion hypothermia. Proceedings of the Royal Society of
jfe&ifcBie, 66, 1058-1061.
Golden, F.S.C., & Hervey, G.R. A class experiment on immersion hypothermia. Journal of Physiology, 1972,
227, 35-36.
Hawryluk, 0, Why Johimy can't march: cold injuries and other ills on peacetime maneuvers. Military Medicine,
1977, 142, m-379.
Hayward, J.S., & Steinman, Ai.M. Accidental hypothermia: An experimental study of inhalation rewanmng.
Aviation, Space, and Environmental Medicine, 1975, 46, 1236.
Jansky, L. Comparative aspects of cold accUmatiKation and nonsHvering thermogenesis in homeotherms.
International Journal of Biochemistry and Biometrology , 1969, 13, 199-209.
Keatinge, W.R. The effects of subcutaneous fat and of previous exposure to cold on the body temperature,
peripheral blood flow and metabolic rate of men in cold v/nter. Journal of Physiology , I960, 153, 166-178.
Kerslake, D.M. The effects of thermal stress on the human body. In J.A. Gillies (Ed.), A textbook of aviation
physioiogy. New Yorit: Pergamon Press, 1965. Pp. 409-440.
I^g, J, Peripheral circulatory adjustment to cold. In A. Borg & J.H. Veghte (Eds.), The physiology of cold
weather turvival (AGARD-R-620). London-: Technical Editing and Reproduction, Ltd., 1974. Pp. 7-15.
21-51
U.S. Naval Flight Surgeon's Manual
Leithead, C.S., & Lind, A.R, Heat stress and heat disorders. Philadelphia: F.A. Davis Co., 1964.
Mills, W.J., Jr. Frostbite, a discussion of the problem and a review of an Alaskan experience. Alaska Medicine
1973,75,2747. ,
Mills, W.J., Jr. Out in the cold. Emergency Medicim. Common Emergencies in Bttay Pmatiee, 1976, 8\ 134-M7.
Minard, D. Physiology of heat sttew. In Department of Health, Education, and Welfare, The industrial
environment ~ its evaluation and eontrol. Washington, D.C.: U.S. Government Printing Office 1973
Pp. 399-412. ^
Mohiar, G.W. Survival of hypothermia by men immersed in the ocean. Journal of the American Medical
Amtdktibn, 1946, 131 , 1046-1050.
Morgan, C.T., Cook, J.S., III, Chapanis, A., & Lund, M.W. (Ede.), Human engineering guide to equipment
design. New York: McGraw-Hill, 1963.
Mundth, E.D. In E. Viereck (Ed,), Proceeding, frostbite symposium. Fort Wainwright, Alaska: Arctic
AeiCi!i>jeUe3ical Lahoir^Oty, 1964,
Sipple, P.A., & Passel, C.F. Measurements of dry atmospheric cooling in sabfii%ezing temperatures. Proceedii^s
of the American Philosophical Society, 1945, 89, 177-199.
117.5. Naval Fl^ht Surgeon's Manual. Prepared by BioTechnology, Inc., under Contract Nonr-4613(00). Chief of
Naval Operations and Bur«ai| of Medicine and Surgery. Washington, D.C., 1968.
Webb, P. Temperature stresses. Li H.G. Armstrong (^d.), A^otpoce medicine. Baltimore: TheWilliteis &
Wilkins Co., 1961. Pp. 324-344.
Bibliography
Anderson, K.L. Thermogenetic mechanisms involved in man's fitness to resist cold exposure. In A. Borg &
J.H. Vegbte (Eds.), The physiology of cold wettthiT mrdweT (ACrARO^B>620). LbttdoM: Technical EiKting
and Reproduction Ltd., June, 1974. Pp. 1-5.
Belding, H.S. Control of exposure to heat and cold. In Department of Health, Education, and Welfare, The
industrial environment - its eeabmtion and control. Washington, D.C.: U.S. Govemment Printing Office,
1973. Pp. 563-572.
Brown, J.R., & Dunn, G.W. Thermal stress: the need for an international standard. American Industrial Hygiene
Association Journal, 1977, 38, 180-183.
Department of the Navy, Bureau of Medicine and SuigeTy. Essential information regarding prevention of heat
casualties (BUMEDINST 6200.7 A). 1977.
Gregory, R.T., & Doolittle, W.H. Accidental hypothermia. Part H. Clinical implications of experimental studies.
Alaska Medkiae, 1973, 15, 48-52.
Grossheim, RX. Hypothermia and frostbite treated witii peritoneal ^^yds. Abskd Medwbm, 1973, IS, 53-55.
Hertig, B~A. Thermal standards and measurement techniques. In Department of Health, Education, and Welfare,
The industrial environment - its eviduation and control '. Washington, D.C.: U.S. Government Printing
Office, 1973. Pp. 413430.
OTDonnel, T., Jr. Acute heat stroke. Epidemiologic, biochemical, renal, and wi^gida^U:sXai^e6, j0iurtUii of the
American Medical Association, 1975, 234, 824-828.
21-52
22
o
CHAPTER 22
TOXICOLOGY
Introduction
General Toxicologic Considerations , ,
Protective Devices and Their Limitations
The CKlorinated Hydrocarbon Solvents
Carbon Monoxide
Carbon Dioxide
Aviation-Oriented Products
Ionizing Eadiation
Special Industrial Hazards
Asbestos and Silica
Irritant Gases
Simple Asphyxiant Gases
References
Bibliography
Introduction
The practice of aviation medicine includes a concern for those chemicals used in naval
operations v^hich are toxic or which give rise to toxic products under conditions of flight or
other occupational use. In order to evaluate toxicological problems effectively, a Flight Surgeon
must be conversant with the principles and practices of conventional occupational medicine and
with problems unique to flight.
Aerospace operations are characterized by rapid increases in technology. As new materials
and chemicals are produced, they may be introduced into use without full knowledge of
undesirable side effects. The Flight Surgeon must remain alert for instances requiring
information which is not yet available in the archives of occupational medicine.
This chapter on aviation toxicology vnll introduce commonly used toxic substances, their
effects on man^ and the initial steps which should be taken to treat individuals who have been
exposed to them. The Flight Surgeon has three responsibihties with respect to the use of these
toxic substances:
1. Medical rendinegs in his own department
2. Education of the user population
3. Lobbying for llie development and substitution of less toxic products.
22-1
U.S. Naval Flight Surgeon's Manual
General Toxicologic Considerations
There are several important aspects of aviation toxicology which should be considered in
establishing appropriate prevention and treatment programs. These are discussed briefly below
and will be considered in greater detail in later sections as they relate to specific toxic -agents.
Hireshold Limit Values
A threshold limit value (TLV) specifies the concentration of a particute sabstaneein liie air
which is believed to be free of undesirable side effects. The TLV is a time-weighted average
concentration which will not adversely affect a person under conditions of repeated daily
exposure. TLV's should not be interpreted as poison thresholds, because they can be exceeded
under certain conditions. Hie American Confereince of Governmental Industrial Hygienists
(ACGIH) publishes these vahies and updates them periodicafly. Current TLV's are available
from ACGIH, Office of the Secretary-Treasurer, P.O. Box 1937, Cincinnati, Ohio, 45201.
Dose-Response Relationships
The occupational physician must be able to assign a safe dose for exposure to toxic
chemicals. The physician should consider whether the dose-response relationship is linear or
curvilinear and whether the response line starts at a zero dose. Several possible dose -response
relationships are illustrated in Figure 22-1.
Figure 22-1. Graph of possible dose-response relationships.
22-2
Toxicology
Routes of Exposure
The Flight Surgeon must be able to identify the portal through which a toxin entered the
system. Four possible means of entry are (1) inhalation, (2) skin absorption, (3) ingestion, and
(4) parenteral (injection or radiation). A common error is to fixate on the portal of entry ^M^s
most obvious to the exclusion of others. Fot esampte, it wotfld do little good to treat a victim
for toxic fiime inhalation if the victim's ctothes continue to act as a teservoir for skin
absorption.
Time/Dose Relationships
With most substances, the medical severity of an exposure is a function of a reciprocal
relationship between the duration of exposure and iJie coneesntraiion of the ehemical. &
concentration increases, there is a shorter period of allowable exposure lime prior to the onset
of symptoms.
Quahtative changes in the effect of certain chemicals may occur as concentration increase^.
For example, in low concentrations various acid gases are inhaM amd thus reach and irritate
hmm rei^iratory tract At hi^er coneentratioM, however, iie gases ^e so irritating to the
upper respiratOfy ■ tract that laryngospasm occurs, op, tihf individual escapes from the
environment before any absorption or damage to the lower respiratory tract occurs. Other gases
(e.g., nitrogen dioxide from rocket fuel) do not irritate the upper respiratory tract and yet will
produce pulmonary edema.
Lnmediate and Delated Effects
While the effects of exposure to toxic substances can occur immediately, very ofteW the
onset of symptoms is delayed. For exarflple, the pubnonary edema resulting from exposure to
gaseous oxides of nitrogen may not appear for 72 hours. Central nervous system (CNS) effects
of carbon monoxide exposure may appear one to two weeks after exposure. Renal shutdown
after carbon tetrachloride poisoning and the true extent of hepatic impairment may not be
evident for days to weeks after tiie incident. The Flight Surgeon should be cautioned that the
seriousn^ of the symptoms which brou^t the patient to medical attention is an unreliable
ind^ of whether delayed effects caw be anticipated.
Individual Variability
There is considerable variability in the response of individuals to specific toxic agents.
Factors which contribute to this variability are the individual's reactivity, his possible
predisposition to chronic effects from an inkilt, his toler«ice level, nutritional state, and
biolo^c idiosyncracies. Environmental factors at the time of exposure, such as the temperature,
humidity, and air flow may also contribute to individual variabiUty.
22-3
U.S. Naval Fiight Surgeoa'a Manual
Metabolism
The presence or absence of specific metabolites can offer dues to the identification of an
unknown toxic substance. For example, inhalatioh hemme stwrfai a detoxification process in
which the benzene ring becomes a pheiiolie ii#ate recoverable in the urine. When it ^ be
shown that urinary inorganic sulfates ffltt bilow a certain level because tbey are bound to
benzene, it can be concluded that benzene exposure did occur.
Of even more vahie to the Flight Surgeon, however, is the knowledge that the actual
metabohsm of inhaled hydrocarbons is extremely slow, if it occurs at dl. Tliese compounds can
be recovered unchanged in ImesAi samples up to ten days after ^posuie, and tiiey are readily
analyzed by spectrometry or gas chromatography.
Pyrolyzation
The degradation by open flame of selected chemicals can substantially increase their
toxicity or change nontoxic substances into toxic ones. Pyrolyzation can fracture carbon chains
Md closed rings and reconstitute the fragments into new combinations with different chnical
significance. The two most dramatic examples of ^ pheiidmenon are carbon tetrachloride and
the fire-eittmguisWng agents of ^e cblorobrontcmiethane famfly. Carbon tetrachloride pyrolyzes
to phosgene, an extremely toxic carbonyl. For flm reason, it is no loi^r recommended as a
fire-extinguishing agent.
Chlorobromomethane pyrolyzes into an assortment of toxic chemicals, including phosgene,
hydrogen bromide, hydrogen chloride, chlorine, and bromine. Long-chain fluorocarbdnsj like
those found in electrical insulation, evolve into new compounds including carbon monoxide,
hydrogen cyanide, liydrogen fluoride, and phosgene. Pyrolyzation of aircraft interiors produces
many of these same toxic by-products, which could be responsible for the death of many
aircraft occupants who actually survived crash impact forces.
Protective Devices and Their Limitations
Selection of the appropriate protective device for the worker using a known toxic substance
depends upon recognition of the toxin's portals of entry. There are two major methods for
protecting the worker: Either the workplace is physically arranged and ventilated to prevent
man-toxin interactions, or the worker is clotiied in giainenfe designed to prevent any contact.
Devices available in the workplace primarily involve ventilation systems which either afford
local exhaust at the origin of the substance or exhaust the entire working area. In general, local
exhaust systems, such as hoods located close to the operation, are an economical and effective
224
Toxicology
means of protection. They do require engineering to obtain maximal effectiveness and
monitoring to insure that the worker uses the system as designed. The chief shortcoming of such
devipes is #«t they may be go hialky that they require an uncottimon commitment from the
worker who uses them. In the aJjsence of supervision, it is likely that the worker will circumvent
systems that he eonsideiB inccmveniiSirt or cufttbeisoaiei.
Exhaust systems designed to deliver sufficient air exchange to the entire working area are an
uneconomical utihzation of energy because of the high power requirements. The FHght Surgeon
should be aware that tiitse exhaust systems, though highly visible and sometimes equally
audfl>le, are a shot^Bli s^proach and often fail to accomplish their purpose. Evduation of the
effectiveness of such systems falls into the purview of the Industrial Hygienist, available as a
consultant from the Regional Preventive Medicine Unit.
Protective clothing and personal protective devices offer an efficient form of protection.
Gloves, boots, aprons, coveralls, face ^tids, andTtiiie Ito fFevent sldn contact. These are
appropriate when dealing with batteiy aMds, Gawistic sohifiom, molten metak, and degreaser
solvent baths, where spilling or splashing is a risk (Figure 22-2).
Figure 22«2. Spattered face shield.
22-5
Toxicology
When inhalation of vapors is the danger, specific guidelines relative to the physical state of
the aerosol must be considered. Respiratory protective devices, when used correctly, offer
^eellmt protec^on for the worker. When Ujsed mi0mM% md Ma occurs frequently, they
afford no protection at all. The classic error is the use^of stfr^cal masks when more ^ecific
protection is required. The three general categories of respiratory protective devices are
(1) mechanical filters, (2) chemical adsorptive filters, and (3) atmosphere -supplying respirators.
Mechanical filter respirators are half -mask facepieces with fibrous filters. Some are approved
for use for silica exposures, while others are acceptable for any mechanically-generated dusts. It
is most important that the Flight Surgeon appreciate that metd fumes such as those generated
in torch cutting or welding operations are not particulate; tiiey are v^orous and are too small
to be filtered by the fibrous element.
Chemical adsorptive filters or camiister MiaMkg provide beds for air flow WWffieh the apedfife
offending substance is selectively removed from the inspired air. Examples of the cannister
contents meant for specific jobs include soda lime for removal of acid gases, silica gel and
activated carbon to remove organic vapors (with the notable exception of carbon monoxide),
and copper or cobalt salts to remove ammonia. The Army gas mask is the classic example of this
type-
Atmosphere-supplying respirators may be either self-contained or connected to a fresh air
source some distance away. The Navy's Oxygen Breathing Apparatus (Figure 22-3), which
generates a 30-minute supply of oxygen and effectively seals the wearer from the noxious
enwonment, should be familiar to every operational medical officer. The air line respirator,
which connects the wearer to a distant fresh air supply throu^ a long hose and a compressor, is
appropriate to the industrial enviroomesit of the shipyard.
The process of air purification using mechanical or adsorptive filters presupposes the
existence of sufficient oxygen in ambient air to support the worker. This important fact is
commonly ignored.
An area of particular concern to the medical officer relates to shipboard "void" entry
(Figure 22-4). A void is a sealed compartment which is available for emergency counterflooding
in a battle situation. Entry to a shipboard void is a most hazardous undertaking. In spite of
safeguards, precautions, and regulations to the contrary, unauthorized shipboard void entry has
acquired a well-deserved reputation as a killer of sailors and their well-meaning rescuers. The
problem is simple asphyxia. The normal oxidative processes taking place in the paint and the
metal of the sealed compartment remove the oxygen from the void atmosphere. Void entry,
^therefore, demands self-contained oxygen. It is predictable that the unprotected sailor who
jenters a vOid will fall victim to the physiologic laws regarding time of useful consciousness! and
lapse into unconsciousness within five seconds (the circulation time from lung to brain), and
tilat a fate awai*S his unprotected rescuer. Their ultimate demise is similarly predictable
and lieedlei^, but temw^ ^
^See discussion of time of useful consciousness in Chapter 1, Fliytiology of Flight.
22-6
Toxicology
Figure 22-4. Entrance to shipboard void.
22-7
U.S. Naval Flight Stirgeon's Manual
The Chlorinated Hydrocarbon Solvents
General Characteristics
Although specific chlorinated hydrocarbon solvents differ in many respects, they do have a
number of characteristics in common. Knowledge of these general characteristics is important in
initial treatment of a patient exposed to one of these solvents. A discussion of ten
characteristics more or less coaiinon to these solvents follows.
Volatility. Because of their volatihty, vapor concentration of these solvents rapidly escalates
to a toxic exposure level. In addition, the risk of exposure to toxic levels increases with
increases in the ambient temperature. It is also worth noting that the purity of a solvent, label
notwithstanding, may be suspect. A classic example is the unlabled benzene contamination of
toluene.
Pyrolysk. Because of their pyrolytic products, open-flame exposure to one of these solvents
could cause substantially greater harm than would occur from exposure to the original
substance alone. In theory, the welder with a cigarette in his mouth can pyrolyze a galaxy of
both the products and the by-products of his work.
X.
Absorption Routes. A solvent may simultaneously enter the. body liirou^ several portals.
When this occurs, cumulative effects greater than those expected from entry through a single
route will result.
Metabolism. Metabolism of these solvents, if it occurs at aU, is so slow that they can be
ric<^ered in the breath for prolonged periods after exposure. Thus, concentrations in expired
lib' are a useful diagnostic tool.
Hepatotoxicity — Renal Toxicity. Hepatorenal toxicity is perhaps the best-known effect of
hydrocarbon solvent exposure. The Flight Surgeon should be aware that appearance of these
effects may be delayed for as long as two weeks after exposure. If the generic name of the
solvent indicates itet it contains a single carbon atdni, dhlorine, hydrogen, and no other
halogens, the chronic hepatic and renal toxicity potentials can be considered a direct function
of the number of chlorine atoms. In ethane/ethylene compounds, the chronic toxicity is a
function not only of the total number of chlorine atoms but also of their distribution on each
carbon atom. It is inversely related to the degree of saturation of the compound. The relative
chronic toxicities of some commonly used solvents are given below.
22-8
Toxicology
Single Carbon Compounds
CCI4 carbon tetrachloride ......= 4+ risk
CHCI3 ehlorofoEm = 3+ risk
Ethane/Ethylene Compounds ,
CH2CICHCI2 1, 1, 2-tricliloEbe^e .....= 2-3+ risk
CClg = GCI2 tetoacUoroethylene . . . . . . = 3+ risk
CHCl = CCI2 trichloroethylene = 2+ risk
CH3CCI3 1, 1, l-tricUoroethane .....= 1+ risk
When the forinuk eontsdils fliidlihe atomic the toxfei^ dSffiinishes with the addition of each
fluorine st&tn; trichlorotrifluoroethane (freon)vwhi<5h has three fhiortne atoms, is benign except
as an asphyxiant.
CNS Depression. Because of their an^thetlc qualities, these solvents* exert « direct ^CNS
depressant effect. Stage IV anesthesia, which may he p&lentiated by tooiria/asphyxia, i^ posible
when dehberate abuse is involved.
Myocardial Sensitization. These solvents have the abihty to sensitize the myocardium to
adrenaUn. Thus, the therapeutic use of adrenalin as pfflft of a wesuseiMfion effort %
conttaindicated. It has been postulated that unexplained sudden deaths after chlorinated
hydrocarbon splvent exposure are due to fatal ventricular urhf^imia tri^red by endogenous
adrenalin.
Degreasing. Since the industrial utility of these solvents lies in their degreasing abilities, it
should not be surprising that they will effectively degrease human skin and cause both acute and
chronic dermatolopc problems.
Systemic Sensitization. This solvent group is well-known fpr systemic sensitization;
generalized or other topical allergic manifestations may occur.
Chemieal Simciure. Open chjto a%hatics are both less toxic and poorer solvents than
closed ring aromatics.
Specific Common Solvents
Carbon Tetrachloride (CCI4). Carbon tetrachloride is a protoplasmic poison and a narcotic.
Perhaps the world's most effective solvent, it enters the body Jihi:|g^#i inhalation an4
absorption. Ijte ht^atotoxicity m primarily osused by Inpstibn, whae matoxieity is caused
primarily by inhalation. In acute exposures, ethanol and pregnancy will potentiate the damage
from exposure.
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U.S. Naval Flight Surgeon's Manual
In addition to causing aU of the general problems associated with the hydrocarbon solvents,
eCl4.can cause optic neudtis. Whethei»ia;fh»flig lowa-of CCI4 poisoning exists and whether
CCI4 should be coaddered a carcinogen has not been definitely established,
Since CCI4 has been prohibited from shipboard use, it should be only of historic value to
the Flight Surgeon. However, it can be found in unsupervised garages and basement workshops.
Methyl CMot^m (IJ.l-trichlome^am). Since it is not significantly hepatotoxic or
renotoxic, methyl chloroform is an acceptrfile substitute for CCI4 and will be found in
electronics repair areas. It is also useful as an aerosol vehicle. It is an effective narcotic if abused,
but only the grossest abuse will carry a patient to Stage IV anesthesia. Like the other
hydrocarbon solvents, it is cardiotoxic and a skin defatter.
r Authorized for use as a metal degreaser only, ttiehloroetiiylene is used
Wider 4&m supervision in pouring new ^pfeoard cross deck pendants. Its use can cause
occasional neuropathies that are self-limited. Workers who have been exposed to
trichloroethylene and consume alcoholic beverages within a few hours usually develop a
'^degreasers' flush," red blotches on the skin caused by intense vasodilation of the superficial
^Ma y»ek. These ©ftfils attd*»rf«eing reports of careinogenicity will probably combine to
remove this soltentfrom authorized use.
The hepatotoxicity of trichloroethylene is probably related to prior ethanol intake.
Heaotoxicity is likely to develop only with a massive exposure, either by inhalation or
absorption. Wm similar solvents, it is cardiotoxic and is a notorious skin degreaser and
sensitizer.
Tetrachloroethylene (Perchloroethylene). Perchloroethylene is remarkably similar in its
toxic properties to trichloroethylene. In addition, it has been shown to be a carcinogen, It is
commonly used as a dry-cleaning fluid. Its primary portal of entry into the body is pulmonary,
and, as is characteristic of the whole solvent group, it can be recovered and identified in a breath
sample as Img U 10 to 14 days after expotee. th^ is a classic accident involving
per<Moroethylene: A user of a freshly dry-cleaned sleeping bag that was not aired before use is
found dead.
Trichlorotrifluoroethane and the Freons. One of the safest and most commonly used
solvent, propeHant, and refrigerant products in the aviation community, Freon 113 is employed
extenrively ia-efectronics repair ' ajH®#i In Miltf^Mf frsage, it presents essentiaUy no
hazard, tiaou^ teehtticany it ii capable of producing all of tKe biblogical and physical effects
22*10
Toxicology
listed in the opening portion of this section. Under certain circumstances, the fluorinated
hydrocarbons that make up the freons produce mild and reversihle CNS depression, can
precipitate cardiac arrhythmia through endogenous adrenalin sensitization, and may be
associated with mild hypotenaon and tachycardia. The real problem with the freons lies in their
deliberate inhalation by individuals who are unaware that the most common effect of such
action is asphyxia.
Benzene. Benzene is an excellent solvent with a bad reputation. It is the parent substance in
the coal tar family. Although it is banhed for household use, it continues to appear disguised as
paint thinner. Acute exposure produces narcosis by vapor inhalation. Benzene's chronic effects
on bone marrow (which m&j regiilt -from hypersensitivity in the absence of chronic exposwre)
present as blood dyscrasias of every known type, including marrow depression,
thrombocytopenic pupura, leukemias, and polycythemia.
Carbon Monoxide
Carbon monoxide (CO) is an odorless, tasteless, colorless gas which is a product of
incomplete combustion of carbonaceous material. The affinity of the carbon monoxide
molecule for hemoglobin is 250 to 300 times greater than that of oxygen. Thus, hemoglobin
will selectively combine with carbon monoxide whenever it is pi^sent, fofmhig
carboxyhemoglobin (COHb), and tissue anoxia will result.
It is difficult to relate laboratory -derived percentages of COHb to clinically -observed effects.
For practical purposes, 30 percent COHb is accepted as the level at which functional
compromise is recognizable; levels greater than 50 percent correlate well with fatal
incapacitation. However, Armed Forces Institute of Paiholo^ records indicate a wide disparity
between measured COHb and ftindtional loss. Carbon monoxide podsons celular respira^ofl, at
the level of the cytochrome oxidase system. The carbon monoxide aeeumulates in the cells by
osmosis from the plasma, not from the red blood cells where it is intensely bound. Since there is
no practical method for measuring carbon monoxide in the plasma, COHb levels are measured
instead. These COHb levels, however imperfect, allow extrapolation to plasma levtds of carlion
monoxide, A conveiuent yardstick for correlating percent COHb, atmospheric concentration,
and functional degradation is given in T Ale 22-1. It should be understood that variance from
this chart reflects the true, unmeasured plasma level of carbon monoxide. This explains survival
at 60 percent COHb and fatality at 30 percent COHb (Goldbaum, Ramirez, & Absalon, 1975).
The relative toxicity of carbon monoxide increases with altitude. This is partly due to the
lower oxygen partial pressures existing at high altitudes. As a result, the onset of "anemic"
hypoxic symptomatology will occur in a shorter time than normal at altitude. The biological
22-11
U.S. Naval Flight Surgeon's Manual
half life of carbon monoxide for an aviator breathing pure air at sea level is one hour. Breathing
100 percent oxygen, the aviator can completely clear the COHb in the same amount of time.
Table 22-1
Effects of Carbon Monoxide Exposure
Atmospheric
Concentration
(ppm)
Percent Blood
Time to
COHb
(80 percent
saturation)
80 Percent
Saturation
(hours)
Symptoms
0- 10
None.
10-20
Slight headache. Tight forehead.
200- 300
20-30
5-6
Headache. Throbbing temples.
400 - 600
36-44
4-5
Headache, nausea, dizziness.
700- 1,000
47-53
3-4
As above. Possible collapse.
1,100- 1,500
55-60
1.5 -3
Syneope, oama, convulsions.
1,600 - 2,000
61-64
1-1.5
As above. Decreased pulse and
respiration. Possible death.
2,100- 3,000
64-68
0.5 -0.75
As above.
3.100- 5,000
68-73
0.3 -0.5
Weak pulse. Slow respiration.
Probable death.
5,100-10,000
73-76
0.05-0.25
As above.
(From Patty, 1963, used by permission of John Wiley & Sons, Inc.).
Tobacco smoking causes increased exposure to carbon monoxide. The one-pack-a-day
cigarette smoker will carry a four to five percent COHb level. The two-pack-a-day smoker will
have an eight to nine percent COHb. COHb levels in nonsmokets range from .5 to .8 percent. It
is ijMjpKGit that the corobiiuition of altitude and increased COHb due to smoking further reduces
inspired oxygen tension and increases the impact of carboxyhemoglobinemia. The aviator who
smokes one pack a day is already functioning at the equivalent of an altitude of 4000 feet.
Engine exhausts contain variable amounts of carbon monoxide depending on the type of
engine and the power setting. For a reciprocating engine, the exhaust contains 8.5 percent
carbon monoxide at takeoff power setting and three percent carbon monoxide at cruise power.
Jet exhaust contains less than one percent carbon monoxide and, therefore, is not of clinical
significance.
22-12
Toxicology
Clinically, tile cherry red color of the victim of carbon monoxide poisoning is well-known,
though perhaps overRtated, since its absence is common (Treanor, 1977). In addition to
coloration, there may be several days of glycosuria, a transient albuminuria, and temporary
ST and T wave changes on the electrocardiogram. Although there is not universal agreement,
most authorities feel that there is no such entity as chronic carbon monoxide poisoning. CNS
comproffiise from a nonfatal but severe exposure may include mental detefktratioii, ttemofs,
and psychotic behavior. For CNS damage, the duration of carbon monoxide exposure is more
significant than the maximum COHb level. CNS symptoms may be transitory, permanent, or
recurrent and may appear for the first time up to two weeks after the incident.
Postmortem findings of COHb levels lower than ten percent can not be eonsidered
significant, even thou^ subcMtiical effeete can be measured experimentaUy. Thsm suhclinicid
effects include a diminution of peripheral li^t perception at four percent COHb and
mathematical computation errors at ten percent COHb.
Sources of carbon monoxide include any internal combustion engine, charcoal stoves,
catalytic heaters, some natural gas heaters, industrial furnaces and ovens, dynamite blasting, and
fire fighting. The propane-burning hot water heaters in the bathrooms of certain hotels Qveriseas
are notorious for producing carbon monoxide poisoning.
Carbon Dioxide
Carbon dioxide is used as a fire extinguisher. Because of the laws of partial pressure as they
apply at altitude, carbon, dioxide is not used within aircraft. Carbon dioxide does become a
toxic hazard in the closed environments of spacecraft and submarines. Carbon, dioxide acts as a
respiratory stimulant at levels of five percent, but, at higher levels, it becomes a narcotic. The
chnical effects of carbon dioxide are related to the concentration and duration of exposure.
Prolonged exposure (over days) to a concentration over four percent can result in death by
carbon dioxide narcosis. A more reahstic example of carbon dioxide narcosis would be death
after ten minutes at a concentration of eight percent.
Aviation-Oriented Products
The Ghlotobromomethane Fire Extinguisher
Halogenated hydrocarbons make good fire extinguishere because, in the process of
pyrolyzation, the oxygen needed to support combustion is removed from the air as the parent
compound is transformed into a myriad of other chemicals. Chlorobromomethane (CB) is the
most frequently used halogenated hydrocarbon. The Air Force uses CB on the flight line and in
aircraft systems for engine fires. The Navy, preferring carbon dioxide for flight line use, uses CB
22-13
U.S. Naval Fli^t Surgeon's Manual
only in aircraft. When a pilot puUs the T-handle in the cockpit in response to a fire warning
light, CB is sprayed on the fire. CB-type extinguishing agents decompose in flame to produce
carbon monoxide, phosgene, hydrogen chloride, and hydrogen bromide. In spite of this, they
are considered safe for the air crew because of rapid dissipation and the distance between the
crew and the extinguisher system, Under unusual ©irci|iosta3ices, the crew and fire fighters may
be exposed to the toxic pyralysis products. These products are discussed elsewhere in this
chapter.
Aviation Gasoline (AVGAS)
The 115-145 octane petroleum distillate fuel used in reciprocating engines has achieved
notoriety for its flammability rather than for its more significant toxicity. This toxicity is not
related to the presence of tetraethyl lead or other xyUdine additives. There are several ways in
which one can be exposed to AVGAS, During handliflg^ storage, or ei^ine maintenance, fuel can
be spilled on clothing. Exposure can also occur when fuel storage tanks are entered for cleaning
or flushing. In these circumstances, AVGAS can be both inhaled and absorbed.
AVGAS fumes are an upper respiratory irritant and produce tearing, choking, rhinorrhea,
coughing, and excess salivation. If these symptoms are not saffidently cKscomforting to drive a
person out of the exposure area, other more dangerous CNS effects may occur. AVGAS causes
CNS hyperactivity, which, depending on the time-dose relationship, can present as simple
excitement, disorganized hyperactivity, confusion, seizure, or death. The clinical picture may be
compUcated by CNS decompression due to anoxia. Treatment should be nonspecific and
supportive.
ilapid vaporization of AVGAS can cause chemical skin bums, particularly when soaked
dotiung or even soaked rags in a pocket are left in prolonged proximity to the sidn.
JP4 and JP5 Jet Fuels
JP4 and JP5 jet fuels have a kerosene base. JP4 is a mixture of 65 percent kerosene and
35 percent AVGAS, while JP5 is essentially pure kerosene. Both fuels contain antifreeze
additives. In vapor form, both fuels are narcotic. Contact with JP4 or JP5 produces severe
conjunctivitis and skin bums unless the fuel is promptiy irrigated from the eye or flushed from
the skin. The sailor who splashes jet fuel in his eye is likely to seek immediate treatment, but
the sailor whose clothiug is soaked with jet fuel may not appreciate the hazard. Contact with
fuel-soaked clothing can cause second degree burns of the affected areas. The severity of these
burns is directly related to the number of hours of exposure, and they are slow to heal.
22-14
n
Toxicology
Prolonged inhalation of jet fuel fumes in a storage tasak xaaj r©gult in CNS d^^^ssii.
Symptoms range from stupor to comdg anoxic seizures, and deatbittAgili, treatment Aotild be
supportive, and, depending on the amount of cerebral anoxia, recovery will be prompt. Tim
Flight Surgeon is cautioned that the victim's clothing may contiime to be a source for skin
contact and fume production and should be removed. All residual fuel must be thoroughly
washed from fhe skin.
Hydraulic fluids ■ > .-^
There are two different types of hydraulic fluid in the in-i^Wy, and each exhibits
distinctly different toxicologic properties. The hydraulic fluid famUiar to most aviators is
colored a distinctive red and is readily identified in smaU puddles beneath certain aircraft. It is a
protoplasmic poison not unlike CCI4, but requires prolonged exposure through either the
inhalation or cutaneous absorption routes to be of chnical significance. Not only is it
flammable, it sh^W'^fe CCl^ the sJiiUty to pyrolyze feito" a. i^^td 'of ^tcfemdy
by-prodacts includir^f&itsgetiei fciiS^tieinergencies accomparued by a fm©«pEaf of this %uid
under high pressure require sufficient ventilation to remove the fumes.
A second type of hydraulic fluid containing tricresyl phosphate is familiar to the operators
(' ) of heavy machinery such as deck edge elevators on aircraft carriers. This green-colored
substance, known as CeUulube, is nonflammable. Unfortunately, it shares a notoriety with the
Moonshine of the ProMbittott «ta that was eontatnttlisd by Jamaica Ginger. Jamaica Ginger,
like Cellulube, contained tricresyl phosphate, a 4WyeUnating neurotoxin which caused
gastrointestinal upset and a poisoning which was known as the "Jake Walk" (Morgan & TuUoss,
1976). The neuropathy caused by tricresyl phosphate, hke the Jake Walk, is irreversible. This
hydrauUc fluid can be absorbed through the skin, ingested, and inhaled. Even a brief exposure,
measured in minutes, eM' Mt€ fraj^c tesilte;' lit p4s^^ respiratory -Mtant
properties, but its neurological toxicity is its primary feature; it cm take a patient througji
Stage IV asdesthesia.
Cellulube or its derivatives can be found in 50 gallon drums at some Physiologic Training
Units for use in the low pressure chamber eompressor and evacuation pumps. Handling of this
material demands the utmost attention to venlilation ttfti' ]^is<iitf *|(i^pifef flfef Ui6 ''<if
coveralls, face shields, boots, and ^ovesis essential. Variants on the SJtfk^t iHi|#tit«[#tliaiyl
phosphate for tricresyl phosphate, but this does Uttle to change the toxic properties. For the
Space Shuttle program, the National Aeronautics and Space Administration has pioneered in the
development of less toxic and less expensive substitutes which appear to have broad apphcabiUty
to the aviation field ("New hydrauUc system," 1976). ' 1 .
22-15
U.S. Naval Fli^t Surgeon's Manual
fti Wolan^ miaMon community & ethyleise gljffeol.
ipeiiil glycol can be a hazard if it is liberated in a mist or spray under low atmospberic
pressure. In this unlikely event, diffuse damage can occur to the CNS, liver, and kidneys.
Deliberate ingestion is more likely to occur; 100 ml is a fatal dose.
Deidng fluids for windshields are usually ethyl, methyl, or iaopropyl alcohols. These present
a rifk of narcofflS from vapor inhalation if iJie concentration and length of exposure are great
enough (a half-hour or more).
Epoxy Resins
Because of their appearance and the protection they offer, epoxy resin finishes will remain
in use. Toxicologically, they are dermatologic offenders of such gravity that the sensitized
worii^r otaust be permanently removed- from future e^osure. The amine hardener, alone or
mixed! with the rean component prior toharderung,i8the principal offender. Proper ventilation
and protective clothing are indicated when epoxy is used.
Fibei^lass
Fiberglass wool, which is used as insulation over pipes and bulkheads, may cause transitory
pruritis. While more often a nuisance than serious, the pruritis is self -limited. This effect of
fiberglass exposure & one of tttpical'irMbitfon and is not a sign of hypersensitivity. It rarely lasts
longer than one week. Kp treatment is required.
C^jp afliJ If ijGlPg Iwnilation
Long chain polymers derived from petroleum and possessing elastic and therm oresistant
properties are the chief constituents of sound attenuation panels and electrical insulation in
aircraft. Pyrolysis of these materials produces lethal by-products which can be broadly
categorized as chemical asphyxiants (e.g., carbon monoxide), pubnonary irritants (e.g.,
phosgene and cUorine), and systemic poisons (e.g., hydrogen cyanide), hohalalton of these
chemicals often prevents the empe of uniiijiw^ idti^^ oeeupWBte who survive ctask impact
forces. The only solution to this problem will be the guhstltution of other materials for these
products.
Smoke Abatement Fuel Additives (CI-2)
Certain aircraft leave a telltale trail of smoke from their engines that allows pinpoint
designation of their position long before the plane itself is *iaMe.i[n order to counteract this
problem, a fuel additive is added direcfly into the fuel tanks. Cleaner combustion allows
22-16
Toxicologjr
smokdefis bunirag saad incf eased combat effeeliveiieii. 33i© ad#^ve.jys metfiyl cydopentadienyl
manganese tricarbonyl (CI-2); it is manufactured as a dark orange liquid which is slightly lliick^
than jet fuel. It is readily soluble in JP4 and JP5. ,
Acute intoxication from inhalation of the CL2 vapors produces tremors and a staggering
gait. The patient may note a strong metalUc tafte in l^e .moii:^ aod experience nausea and
vomiting. CI-2 can also be {Absorbed #rou^ the i^dn md isniil^y hmmful H i^laehed in,to the
eyes. Use of protective clothing in handling the additive is mandatory. In the cleanup operation
after a spill in a closed space, full respiratory protection is also required; immediate
decontamination is the backbone of first aid. Although there is no substitute for a vigorous soap
and water scrubdown for the victim of an accident with CI-2, its solubUity in jet fuel makes this
a pfae^cd fh$t-aid measure for emergency temoviA of j|ie ag^t if&m the itelp.. Specific
treatment is aimed at chelation of the manganeM, even Ihtou^ iappctrtive evidence for this
rationale is scanty. The drug of choice for this purpose is Galdum Disodium Vereenate^.
Agricultural Aerial Application of Pesticides
Pesticide poisoning may seem to be of httle importance to a Navy FUght Surgeon, but some
Navy bases are located in rich agricultural belts where knowledge of pesticide toxicology will be
helpful. Non-aviation-oriented colleagues expect Flight Surgeons tEf b® fcaowledgeable about
pesticides because they are delivei-ed by aeM UpphiatitQitii -An: ^isebUeiitt wall ehfOrt whtih
aiccinetly ©overs most commonly used pesticides is available from the U.S. Navy Disease Vector
Ecology and Control Center, Naval Air Station, Jacksonville, Florida, 32212. The chart is titled
"The emergency treatment for acute pesticide poisoning (Misc-348).''
'J- • • . ■
One brief and oversimphfied distinction must be made m the selection i^^the appropriiEifc©
treatment for pesticide exposure. It must be ascertained whether the pesticide is an
organophosphate that depresses blood chohnesterase activity and for which theiei^^ft G|>edfiG
antidote, or whether it is a chlorinated hydrocarbon which requires supportive treatment oidy.
BeryUium Brakes
The physical properties of berylhum make its use desirable where resistance to great heat
and friction are needed. BeryUium brakes joined the Navy inventory with the introduction of
the f'-14 and the S-3 s^craft. With them came three related proUems: beryllium pneumOttWi^,'
berylHuM ipiilmdnafy granulomatosis, and beryUium contamination of sMn laceraMons.
BeryUium pneumonitis acts like the classic pneumonitis where the X-ray looks worse than
the patient. In rare cases, it progresses to a pulmonary fibrosis in later years. Death from the
acute pneumonitis stage is uncommon. The pneumonia can appear up to six weeks after a
22-17
U.S. Naval Fl^t Surgeoii'e Manual
beryllium exposure of 1 to' iO dafs''duratiott' ind can require up to ax months to tfesolve.
St^i^l^ aintibiotics, and other supportive measures stt indicated. It is pdstulatisd that Beiyllittm
pneumonitis is a response to the pulmonary presence of soluble beryllium salts or beryllium
oxide.
BeryUium pulmonary granulomatosis is the most feared form of reaction. It appears weeks
to years after the initial exposure and closely resembles sarcoid in that it is not merely
pulmonary in focus. There is no coixelation between iratposute intenrfty and this reaction. As
might bf^ expected with any chronic lung disease, pulmonary hypertension with cor pulmonale,
ultimate right heart failure, and pulmonary insufficiency are sequlae of progressive beryllium
intoxication. The clinical picture is one of exacerbation and remission. The diagnosis of
beryllium pulmonary granulomatosis is made 'mostly by history and by excluirfon, since thfflfe is
no reliaUe method for beryfliura assay, and the X-ray is nonspecific. Overall mortahty from this
syndrome has been estimated to be as high as 30 percent and as low as two percent.
A third syndrome involves imbedded beryllium dust particles in open wounds. It results in a
chronic sore that requires excision for healing to occur.
The key to protection is that the only threat from beryllium comes from dust-sized particles
that are either in aeroa©! or ate allowed tp copae ip Coiitact with an open wound. Overheated
beryUium brakes should be air-cooled without theidd of coohng water, which would produce a
cloud of beryUium -laden steam, or high pressure air, which would mobilize whatever dust was
present. Personnel with open cuts on their hands should not be allowed to handle beryllium
brake parts. After handling beryUium brake parts, one should wash the hands before eating,
drinJdng, or smoking.
B@l^llio;sis causes no increased risk for either tuberculosis or cancer.
Polyurethane Paints
Polyurethane paints are used because they are particularly corrosion-resistant. They contain
toluene diisocyanate (TDI). Five percent of the population is readily sensitized to this chemical
and wiU present with acute bronchospasm^ even in the absence of any prior aUer^c history.
Because the production of heat and the evolution of gas are involved in the polyurethane curmg
process, TDI vapors are released into the atmosphere. Clinical experience with TDI shows that it
is a potent irritant of the eyes and upper airway. With prolonged exposure, a nonspecific form
of bronchial irritation develops and includes dry cough, chest pain, and hemoptysis. Between
this stage and the fuU-blown bronchospasm stage, there may be an additional stage of fever and,
mala^e wjdiout X-ray changes. The bronchospastic stage may be so sev<we as to include cyanods
22-18
Toxicology
and collapse. The existence of a chronic stage has not been demonstrated. In addition to
receiving symptomatic and supportive treatment, the patient who has demonstrated sensitivity
to TDI must be permanently protected from further TDI exposure. The FUght Surgeon should
note th&t the symptom compleK can develop not only in unprotected workers who inhale
polyur^dtane paint particles but also in hanger occupants who breathe vapors from tiie curing
paiiit on aircraft.
Although the general use of polyurethane paints is limited to authorized Naval Air Rework
Facilities, they are found elsewhere. In addition, the use of polyurethane paints for touch-ups is
approved and should be monitored.
Ionizing Radiatioti '
Nondestructive metallurgical testing of airframes may iuQlude the technique &i X-isf'
photography. Because the Flight Surgeon is mole felowledgeable abbtit IhiShmi^ of
radiation than most members of the command, atttd sinice technicians who are not part of the
command will be present, it is imperative that the Flight Surgeon assume responsibility for these
endeavors. He should supervise the safety precautions relative to where the X-ray unit is
physically placed, where the scatter radiation wiU go, and what offices or shops may be located
behind aluminum bulkheads in the line of the examining beam. Th^ reipOlldbiltSefe obvioia^
caimot be &charged from the privacy of an office in fflckbay or the digpensary. '
Spedal Industpal Hmwcds
Welding
Three particular hazards exist for the welder, his helper, and bystanders. They
are (1) corneal and conjunctival nlti-aviolet bums, (2) metal fume fever, and (3) heavy metal
fume poisoning. A discussion of each of these hazards follows.
Corneal and Conjunctival Ultraviolet Bums. In Order to protect himself from ultraviolet rays
given off from the flame source, the welder wears an impervious face plate. It is uncommon to
see a welder working without his face plate, but it is very common to see his helper, "the fire
watch," either looking directiy at the torching operation or standing in an area wiief»
^sotbing Inflected rays from adjacent surfaces. The cornea and aqueous humor absorb
essentMy afl iflteviolet radiation rnddentttpon'Sie eye? veiff ttttie penetrates as far as the lens.
Exposure to ultraviolet rays can produce blepharitis, conjunctivitis, keratitis, and
kerato-conjunctivitis. Typically, the symptoms are delayed a number of hours after the
exposure so that the victim presents with "midnight conjunctivitis" as a result of the day's
exposure. The correct diagnosis is readily made with a history and the physical findings of
2249
U.S. Navai Fl^t Suigeon's Manual
spotty fluorescence u|^tdke hf the cornea. iTreatdieftf, consigting <d bilateral patching,
initlUfltion of antihiotie drops, and systemic analpiik, wfD effect a mt& wi^tt 12 to 24 hoiirs.
Metal Fume Fever. Any operatioii which gives rise to freshly generated metal fumes is
capable of producing a flu -like syndrome. This results from the inhalation of a^omerating
particles which range in size from one to five microns. Interestingly, the worker acquires an
inunumity from xsontiituous exposure. This immunity is so sh(Mi:«Hved, however ^ that a weekend
away from the fume environment can result in an attack of metal fume fever at the beginning of
the next work week.
The symptoms of metal fume fever develop several hours after an exposure and, classically,
after the workday is over. The symptom complex begins with a shivering chill and is followed
by a fevar ^of 102 to 103 d^ees for about 12 hours, Ql^er key S3rmptoiiis irtchtde lassitude,
myalgia, a sweet taste in the mouth, burning eyfcs, said dry throat. After the incident, an
impressive leukocytosis persists as long as the temporary immunity lasts.
Brass, copper, zinc, iron, and magnesium are among the offending metals, but it is likely
A«t almost any metal can produce the syndrowe. A 4inilar illaess csQed "IPolymef Fume
Fever" is known in the industries that manufacture teflon polymers (Kuntz & McCord, 1974).
Heavy Metal Fume Poisoning. The welder or cutting torch operator can find himself
exposed to very dangerous, poisonous fumes. The most harmful exposures occur with cadmium,
chromium, lead, and nickel. Any welder or torch cutter who presents in respiratory distress
should be considered a potential victim of pulmonary edema which may take up to 48 h^UTS to
be cUnieatty visible. TTie only reason that there are not more of tiiese poisonings is tibat the
majority of such risky operations are performed where ventilation is adeipiate.
Cadmium
Cadmium oxide fumes can be produced by soldering, welding, and blowtorch cutting. In
aerosol form, cadmium causes mild respiratory irritation. This symptom is usually ignored. An
apparently iimqcuous flu4ike sjmdrorae, which may cause the worker to seek medical attexitLon,
follows. At this point, the individual risks progression to full-blown pulmonary edema which
may occur a day or so later. The mortahty rate after severe acute exposures to cadmium oxide is
15 to 20 percent. Chronic exposures may lead to pulmonary fibrosis, and inhaled cadmium can
predispose to emphysema ("Cadmium and the lung," 1973). The possibility that cadmium
oxide is a carcinogen also exists.
22-20
Toxicology
Chromium
The dusts and mists associated with the chromium plating process are recognized as
dangerous. Unfortunately, a welder may be unaware that there is clii6m&]ni M ^ ^hM.
Hiou^ pulmonaiy edema from these fumes is unlikely, ''chromium bronchitts" and '*tjtftf&toi
holes," which are skin ulcerations and nasal perforationfi, are well known in the industry. Some
observers have described an acute "chromium pneumonia." Chromate paints are uWd
extenrively &i 1km aviation environiBeiM: as an under cc»«t for ©orroaon control.
Lead
The high temperatures generated by oxyacetylene flame torches for metal cutting will
vaporize lead-based paints. Red lead paint is common in the naval environment. Lead fumes
exert a ouiiiti&itfVfe effect. The prophylaxis for lead is respiratory fttitection. fts^^^dififfe
chelation is not ^ifective, "tfiou^ it hm been recomffiended by some sources. The Flight
Surgeon should refer to more definitive sources for a complete dissertation on the complexities
of lead poisoning. When suspicious of lead poisoning, the physician should take an occupational
history and remember the acronym "lead CAPER." The lead CAPER is ' ' '
C = coUc
A = arthralgia i .
P = painless polyneuritis
E = encephalitis
R = red blood cell stippling and anemia.
Nickel
Where chrome plating is present, a nickel undercoat wfll h$ found. Nickel-cadmium
batteries, the mf^nstay of many airlotne ''^lack Iboxes," can present a toxicblo^c nightmare for
^ uninitiated torchcutter. Nickel fumes caiise a "nickel itcV' which, at the least, is
i^avaliHg. More importantiy, the welder's torch will cause the release of nickel carbonyl, a
toxic gas that causes a nickel pneumonitis and can act as a chemical asphyxiant in the tradition
of hydrogen cyanide. Nickel pneumonitis should be treated with complete bed rest,, steroids,
and antibiotics. Nickel, nickel carbonyl, and perhaps other nickel compounds must be
considered potential carcinogens.
General Considerations
The pneumoconioses resulting from inhalation of asbestos and silica duste are progressive
diseases that can be initiated by casual exposures which defy the rule of time-dose relationdiips.
22-21
U.S. Naval FHght Surgeon's Manual
Most often, however, occupational exposures precipitate the process. Asbestosis and silicosis
ffoare a coarse collagen fibrosis of the pulmonary parenchyma either with or without nodularity
the basic pathology. They differ in their sites of predisposition within the lung and in the
!^^g]ipa^9:|is tjiat are a predictable risk.
Asbestos
This ubiquitous substance is an occupational hazard in the shipyard. Asbestos bulkhead and
pipe lagging are used to decorate and insulate iron, steel, and aluminum surfaces throughout
ships. Fragmentation of the individual asbestos fibers to an inhalable aze (20 to 50 x 1 micron)
#0ws their impingement on &s pulmonary parenchyma where the ensuing mechanical
jkritafion causes reactive fibrosis in the lower lobes/ Some # these fibers migrate to the pleura
^U3u} peritoneum), probably mechanically, but the lecoymy of asbestos fibers from pnhnonary
secretions is not a reliable indicator of their pathologic presence. The fibrosis that results is not
patterned along lymphatic or vascular hues, but is nonetheless progressive. Asbestosis
predisposes to both carcinoma and mesothelioma; smokers are at increased risk for these
compHeationSt Wherever possible, fiberglass should be aibstituted for asbestos; where
substitution is impossible, respiratoiy protection is not only prudent, but is required. There is
no acute phase of this illness; it is a chronic, progressive disorder that is irreversible and
compensable. The Navy has a well-thought-out program for the control of asbestos exposure
that will be of interest to the involved Flight Surgeon (BUMEDINST 6260.14).
Silica
The earth's crast contains variable amoiuits of silica (Si02). Inhalable Si02 dust particles,
like those made airborne by earth-moving equipment in the preparation of a landing strip,
initiate a ftbrotic jp^ocess in the upper pulmonary lobes. There is evidence to suggest that an
immunologic response is involved; the site of the pathology is along lymphatic tracks. Larger
particles travel the local pulmonary lymphatic system before a^egating into an immovable
size, while smaller ones cause their damage at the site of deposit. This is reflected in the variable
dincial picture, which can be macronodulur or fibrotic. Both types result in parenchymal
^pmpression, distention, distortion, ultimate focal emphysema, and atalectasis. Silicons
predisposes to tuberculosis; both of these ^seas^ are apical. The length, of time from the
offending exposure to the recognition of disease apparently obeys the rules of time-dose
relationships, but the time frame can vary from as short as 18 months to as long as 20 years. As
with asbestosis, smoking increases the hkelihood of complications. Sihcosis has no acute stage; it
is a chronic, progressive disorder tiiat k iprevteissible and compensable.
Toxicology
Irritant Gases
The potential toxicity of an irritant gas can be determined by its solubility. This property
can alert the Flight Surgeon to the anticipated chnical syndrome that will result from inhalation
of an irritant gas, evett when knowledge about the particular gas is scanty. To explain this, the
pulmonaiy tree must be divided into U|»per, middle, and lower sections. A soluble gas will cause
immediate upper respttatox^ trast ^mp^tams «f Inttatlon such as rhinorrhea, choking,
laryngospasm, acute glottic edema, and coughing. This symptom eomplex is usually
uncomfortable enough to force the victim to quickly leave the site of exposure and thereby save
himself from the more serious consequences that would follow from lower tract involvement. A
less soluble irritant would have its site of action in the major portions of the bronchial tree itself
and would cause bronchitic symptoms and t^est discomfort. DepignJi^ on the length of
exposure, this could be serious. For insoluble irritants, the palient need not suffer any
immediate subjective compromise, and the damage can become extensive as the irritant becomes
implanted in the alveolar spaces of the lower respiratory tract. The most serious consequence of
lower tract irritation is pulmonary edema. To make matters worse, the extent of damage may
not be cliiiicidly obvious for up to 48homfe. This pulmonary edema amounts to tissue
compromise somewhere between a bum and frank necrosis and is difficult to treat. Some
common irritant gases and the relationship between their sohibihty and irritation site are listed
below.
Upper Tract Irritant
(soluble)
Ammonia (NH3)
Acrolein (C3H4O)
Formaldehyde (CHgO)
Hydrogen fluoride (HF)
Hydrogen chloride (HCl)
Middle Tract Irritant
(mildly soluble)
Sulfur dioxide (SO2)
*Chloriiie(a2)
*Broinine (Br^)
*Iodine (I2)
Lower Tract Irritant
(insoluble)
Nitrogen dioxide (NO2)
Ozone (O3)
Phosgene (COCfa)
May be considered as both middte and lower tract irritants.
Simple Asphyxiant Gases
If an individual has been exposed to a simple asphyxiant gas and requires resuscitation, it is
important the gas be recognized as a simple asphyxiant. Eroper treatment requires
eoi3?ection of anoxia. The fact that the gas is biologically inert removes all the considerations
appropriate to inritant gases for which the risk is delayed pulmonary flfcema. By the law of
partial pressures, simple asphyxiant gases displace and thereby reduce the total amount of
oxygen available. Physiological decrements are associated with available ambient oxygen levels
bdow IS percent (Table 22-2).
22-23
U.S. Naval Flight Surgeon's Manual
Table 22-2
Physiologicai Decrements Below 18 Percent Oxygen
Percent
Ogin Air
Physiologic Effect
18
No observable effects (OSHA lower limit)
12-14
Increased pulse and respi^ion
Diminished coordination
10-12
Giddiness, poor judgement; Circum-oral cyanosis
8-10
Nausea, vomiting; Ashen facies; Unconsciousness
e-8
LD^° at six minutes; LD^O" at eight minutes
4
LD^'*^ in40sed[}nds
Sittple a8phys:i#t pm$ are listed below.
Simple Asphyxiant GoKg
Methane Carbon Dio^de Nitrogen
Ethane Nitious Oxide Argoii
Acetylene Hydrogen Neon
Helium
Referencea
Cadmium and the lung. The Lancet, 1973, 1134-1135.
Department of the Navy, Bureau of Medicine and Surgery. Asbestos' matures fra control of
(BUMEDINST 6260.14).
Goldbaum, L.R., Ramirez, R.G., & Absalon, K.B. What is the mechanism of carbon monoxide toxicity?
Aviation, Space, and Environmental Medicine, 1975, 46, 1289-1291.
Kimtz, W J)., & McGord, CP. PcJymer fume fever. Journal of Oecvt^tional Medicine, 1974, 16, 480-482.
Morgan, J.P., & TuUoss, T.C. The jake walk blues, a toxicologic tragedy murored in American popular music.
AnnaU of Internal Medicine, 1976, 85, 804-808.
New hydraulic system fluid selected. Aviation Week & Space Technology, November 8, 1976, p. 90.
Pat^, f.A. (Ed.). Industrial hygiem and tasAeolog^. Vol. H. toxicology (2nd Rev. ed.). New
TiSft: :bterBraence Pobtidbim, 1963.
iWnor, IJ. ^d weather a^iaSon p^dioloj^: a oi^e report. Aviation, i^icuXf OHd EitbummenM MesMeme,
. 1977, 48v 377^79. '
22-24
Toxicology
Bibliography
The following books and articles give more definitive information on the hazardous
substances outlined in this chapter.
Department of the Navy, Bureau of Medicine and Surgery. Trichloroediylene; health hazards of (BUMED
Instruction 6260.22).
Dreisback, R.H, Handbook of Poisoning (8th ed.). Los Altos, Galifortda: Lahge Medical PuUications, 1974.
Hamilton, A., & Hardy, H.L. ladmMat toxicology (3rd ed.). Acton, MassachuBetls: Publieliing Sciences Group,
Inc., 1974.
National Institute for Occupational Safety and Health, Health, Education, and Welfare Department. Industrial
environment, its evaluation and control. 1973.
Patty, F.A. (Ed.). Induttrial hygiene and tomoiogy. Vol. 1. Genend principles (2nd Rev. ed.). New
Yoric: htttqisqieuoe PuhliaherSi 1958.
You^e the fli^t surgeon. Avia^n, Space, and Environmental Medicine, 1976, 47, 674.
22-25
Al
o
c
o
c
CHAPTER 23
EMERGENCY ESCAPE FRCW AlRiClRAW'
Introductioii
Escape Systems
Pre-ejection
Dynamics of Ejection
Airstream Entry ^
Parachute Descent and Landing
Ejection Acddent Summaries
Pattern of Ejection Injuries
Special Escape Problems
Training
Future Escape and Survival Systems > ■ •
References v . , ,.iir»i
Introduction
It has always been Navy policy to do the utmost to insure the sai^ety and survival of Navy
aircrewmen. An example of this policy is found in the sophisticated escape systems now used in
high-performance aircraft. To rescue an aviator tt&m a disabled aircraft - one which might be
travflmg %t high speed, totally out of contrcl, ali4 rapidly disintegrating - is a marvelous
accomplishment. That it can be done successfully is a tribute to many disciplines and
individuals. The engineering sciences contributed basic system designs. Test personnel, at great
personal risk, demonstrated that these systems would work. Medical scientists provided the
necessary information concerning human tolerance limits and participated directly in early test
programs.
There is a continuing requirement for medical personnel in naval aviation to be
knowledgeable about aircraft escape systems. Flight Surgeons ftstvie iftiiltiple respohsibaitleS &
this regard. First, a Flight Surgeon must understand the operation of escape systems if he is to
deliver effective lectures to aviators concerning the stresses placed on the hatom body during an
emergency escape and the proper prscedures required to minimize these stresses. A Flight
Surgeon must be prepared to mtswef queslions concerning all of the biomedical aspects of
escape.
23-1
U.S. Naval Fli^t Surgeon's Manual
The second responsibility of a Flight Surgeon is to have a clear understanding of escape
forces so that he can diagnose and treat the unique injuries Ukely to be received by an
aircrewman. An aviator who is suddenly propelled into a windblast of several hundred knots can
be subjected to unusual and very dams^g eompression and torsion forces. When a rescued
aviator is returned to a carrier, the Flight Silicon must be able to recognize the ejection injury
syndrome immediately and to deal with it effectively.
A third responsibihty for a FUght Surgeon is to understand the entire escape process
sufficiently well so that he can provide system designers with feedback information concerning
Fleet use of escape equipment. The Medical Officer's Report of an aircraft accident remains a
primary source of information concerning the operation and effectivene^ of aircraft escape
systems. It is obvious, however, that the real value of these reports is bounded by the
knowledgeabiUty, effort, and care of the contributing Flight Surgeon.
Escape Systems
The first successful human extraction from an aircraft was accomplished by Army
Lieutenant Solomon L. Van Meter in a JN4D "Jenny" at Kelly Field in March 1919, Van Meter
initiated this extraction by activating a heavy spring-loaded cannister which contained the
parachute canopy. This action propelled the parachute some 20 feet upward in space and
unbuckled his seat belt, clearing Mm for es^pe. The force of the wind fiUed the parachute and
jerked him free of tbe aircraft (Jones, 1974).
It was not until the advent of high-performance aircraft, however, that the development of
aircraft ejection and extraction systems began in earnest. During World War 11, it became
obvious tiiat tiie speeds attained by fighter aircraft made bailout extremely hazardous, if riot
impossMe. Severe windblast prevented individuak from clearing tiie aircraft and caused
premature deployment of parachutes, EjEcegave G-forces in spinning aircraft often immobilized
aircrewmen, and high sink rates in a power-off configuration often negated any chance of
low-altitude escape. In 1945, both Great Britain and the United States were developing ejection
seats to be used in jet-propelled aircraft. On 30 October 1946, Navy Lieutenant (jg) A. J. Furtek
made the first live test of a U.S. ejection seat when he was safely blasted from a JD-1 flying at
about 250 knots at 6,000 feet over Lakehurst, New Jersey.
Ejection Seat Operation
Present Navy ejection seats are highly automated systems requiring the pilot only to pull a
firing mechanism to effect escape. Typically, the seat consists of a seat bucket, back, and
headrest assembly with attached boost catapults to propel the seat and pilot from the aircraft.
23-2
Kmergenc^ Escape From AirciiCEt
Sustaitter rocket motors provide increased trajectory. Subsystems include stabilizing devices,
parachutes, and survival equipment.
The type of seat propulsion (most now are rocket augmented), and the methods of
extremity restraint, seat separation, chute deployment, etc., wiU vary among the ifarious types
of ejection seats. All systems, however, are amilar in overall concept. Figure 23-1 shows the
sequence of events which occurs during an ejection using the Rockwell International HS-lA
ejection seat system. After making the decision to eject, the aviator positions himself in the seat,
with buttocks well back and head firmly against the headrest. This position minimizes stress on
the anterior portion of the vertebrae during seat acceleration. Generally, escape is initiated by
the actuation of either a face ©urtain or a lower firing controL T^efaee curtain, located at the
top of the headrest, Is grasped wi& the hands, palms tovrard tfie head. The curtjairi is pulled
down over the face with elbows held in. Initial movement of the curtain fires a canopy release
mechanism; the final movement fires the seat itself.
Under asymmetrical flight conditions or when acceleration forces exceed 6 to 8 G, the face
curtain may he difficult to reateh and/or actuate^ Aviator injury, blockage of accefs to the
curtain by the aviator's head, or lack of sufficient time could also prevent usage of |he ijice
cUftaxn. Accordingly, a lower firing handle is located between the legs at the forward edge of #ie
seat bucket.
As the ejection seat starts up the guide rails, the lower extremities retract back against the
seat and are forcibly held in that position by a leg restraint system until a seat separator
mechanism is triggered. During seat travel up the rails, the automatic lap belt releasesfeystem is
armed, and oxygen/communication disconnects are separated. As &e seat continues upward, a
rocket attached to the seat structure is ignited. The rocket assist provides a number of desirable
features over the older, multiple cartridge system. The rocket propulsion acts as a sustainer,
maintaining propulsion after the normal catapult tubes have separated. A higher ejection
trajectory results. The higher trajectory assures that the ejected ttian^at combination wiU clear
aircraft stnuliires, m^h m the tail, duritig h^ @pe«d escape. In addition, in maily ^stemg> the
higher adtitude is ngisessary during low spmA saut zero-zero (zero velocity and zero altitude)
ejections to prpi^de mfificient ^me f or dssploymeftt and opening of the persqranel parachute-
The rocket system helps to overcome the problem imposed by human tolerance to impact
acceleration and its restriction m escape trajectory height. Thus, 'h%h trajectories can be
achieved within the limits of humati tolerance. Ifegt rodtet seats are Capable of saving the
occupant under zero-zero conditions.
23-3
®
®
Face Curtain (or secondary ejection handle) Pulled
• canopy jettisoned
• seat bucket is bottomed
• shoulder harness retracted
• retention devices actuated
• rocket catapult fires
• seat travels up rails
• emergency actuated
• emergency I FF actuated
• drogue parachute deployed
Drogue Opens
• seat "flies" up and forward, stabilized by rocket
thrust vector through man/seat center of gravity
and drogue chute
Above Barostat Setting {10,000 feet)
• man descends in di-ogue stabilized seat
• emergency O2 supplied
^3^ (continued}
Below Barostat Setting (10,000 feet)
• drogue chute risers disconnected
■ retention devices released
• face curtain released
• seat separation bladders actuated
• recovery parachute deployed
• man removed from seat
(4) Recovery Parachute Opens
• radio beacon actuated
Manual Tasks
• D ring removed from harness
• oxygen mask removed
• survival kit deployed at discretion
of airman
• landing position assumed
Figure 23-1. Ejection sequence (adapted from U.S. Naval Flight Surgeon 's Manual, 1968).
Emergency Escape F{tQ)in| Aif^i;^.
Navy ejection seats employ three general types of stabilization systems (e.g., drogue
parachute, brake line, or gimballed rocket motor) to insure optimal use of sustainer rocket
motor thrust and to prevent potentially injurious tumbling of the man-seat combination. These
seats may also differ markedly in the manner of effecting man-seat separation and parachute
deployment and opening. Some of the^ more CQm,raonly u^d'^f terns wiH be dis<ii8ged?fe.te
ne-^t section. : ; ;
CuirentNwy Ejection SeaK
Navy aircraft currently use a variety of ejection seats. Table 23-1 lists these seats and the
manufacturers. The foUovnng section describes some of the physical and performance
characteristics of the three most common seats. The FUght Sui^eon should recognize, however,
that configurations and performance characteristfdl' of ejection' 'se^ ^kry greatly among seat
types and with modifications to a specific seat. He should insure that he refers to an up-tO'date
NATOPS manual or Maintenance Instruction Manual (MIM) when attempting to obtain
information on a specific escape system.
Table 23-1
Ejection Seats Used in U.S. Navy Aircraft
Navy Atniraft
Ejection Seat
Douglas ESCAPAC-IC-3, IF-3 and IG-3
A-5
Rockwell Intemational HS-1
A-6
Martin-Baker MK-GRUS and MK-GRU7
A-7
Douglas ESCAPAC IC-2 and rQ-2
Martin-Baker MK-H5 and MK-H7
F-8
Martin -Baker MK-FS and MK-F7
F-14
Martin-Baker MK-GRU7A
F-18
Martin -Baker MK-tO
S-3
Douglas ESCAPAC IE-1
T-2
Rockvvell International LS-1
AV-8
Stencel SEU-3/A
OV-10
RiMill International LW-3B
Douglas ESCAPAC Ejection Seat, Series lA Through IG. Following seat initiation, the
operation of the Douglas ESCAPAC seat (Figure 23-2) is fully automatic and allows escape
during level-flight conditions fi'om zero altitude and zero speed, tfrnou^ 600 KEAS (klt^l^
23-5
U;S. Naval Bli^t Sturgeon's Manual
e*^ated speed) (ligi»e S3-3). The system will dlow safe eseapfe uiidisr sink rate
conditions of up to 4,000 feet per minute at ground level. The seat incorporates a rocket
catapult propulsion unit integrating both the sohd propellant cartridge and the sustainer rocket
motor. The catapult stage launches the seat at an acceleration of approximately 12 to 15 G. Leg
restJdnt k pas^ve and is pfovided by extended seat sides. In some models of ESCAPAC, a
mechanically fired rocket located under the seat bucket is designed to stabilize tiie seat
throughout sustainer motor thrusting. In other models, a brake line is employed to provide seat
stabihzation. The thrust of a small rocket is used to separate the man from iie seat into a
divergent trajectory. As the seat and man separate, the parachute actuator is armed and the
external pilot chute is deployed. Opening of the main parachute follows. Just before parachute
line stretch, a btilHstic spreader gun is fired to forcefully initiate parachute inflation. The
NES-12 series parachute assembly, used in this system, employs a 28-foot circular canopy .
Figure 23-2. ESCAPAC IE-1 ejection seat
(Courtesy of Dou^as Aircraft Co.).
Martin-Baker Ejection Seat Mark 5 Through Mark 10. The Martin-Baker Mark 5 ejection seat
employs a three-cartridge pyrotechnic-telescoping, long-stroke ejection gun which achieves an
®0-foat' pea- second ejection with ittaxiBiUih' kcbeleration of 15 to 18 G. The Mark 7 seat
28*6
Emeigen<^ Esci^e From Aiicriift
(Figure 234) differs from the Mark 5 seat primarily through the addition of a rocket pack,
which lessens ejection acceleration forces acting on the spine. Parachute deployment in
Martin-Baker seats is aided by the use of a drogue chute. The parachute has a 28-foot canopy
and is positioned behind ihe crewman's shoulders. The leg restraint system consists of garters
which are worn by crewmembers (Figure 23-5). The Martin-Baker Mark 10 seat (Figure 23 6) is
a zero-zero seat providing escape capability up to operating speeds of 600 KEAS. Seat
propulsion is by ejection gun and rocket, with peak acceleration between 14 and 16 G.
Stabilization for these seats is accompbshed with drogue chutes. The drag load of tibie stabilizer
drogue chute is transferred to the personnel chute, thereby insuring seat-man separatipit affibr
the parachute is deployed.
]$giU6 23-3. ESCAPAC IH seat performance for aircraft in levd fli^t
(Courtesy of Douglas Aircraft Co.).
North American Rockwell Seat (HS-IA). The North American Rockwell HS-lA seat
(Figure 23-7) uses a catapxdt rocket motor to provide emergency escape from zero to 750 KIAS
(knots indicated air speed) (Figure 23-8). The catapult portion of the rocket firing provides
relatively high impulse with maximum acceleration around 20 G. The rate of acceleration is
approximately 250 G per second. The HS-lA seat possesses a rigid leg restraint system. During
the initial phase of ejection, leg positioning and restraint and positioning of the lower torso are
accomp&lmd by Imi^mg the seat bucket to bottom, liftitig the knees, and locking the feet in
foot wells. The knee-raising bar contacts the legs behind the knees. As the knees are lifted, the
feet fall into the foot wells which are closed by hooks. If acceleration is being experienced, such
that the feet will not fall into the wells, the closure hooks contact the lower legs, pushing the
feet into the wells. The NB-7E parachute is extracted from its pack by a drogue chute. When the
line stretch of tfee main parachute is mefeed, the spreader gun fires to ensure rapid inflation at
low speedfip. iPitttchuf ®»©p«niJ3^ forces sep'arate the man from the seat.
( /
23-7
U.S. Naval Fli^t Soigeon's Manuid
Figure 23-5. Proposed Martin-Baker ejection seat
leg restraint (doujile garter) configuratioii
(Courtesy of Afartin-Badcer Anciaft Co, Ltd.).
23-8
Emet^ncy Escape Ftotn Aircraft
I 1
300
250
I-
UJ
lij
I-
X
o
ui
X
_l
<
o
H
oc
LU
>
100
1 1
MARTIN-BAKER
\
1
:hute
NFLA
HON
EJECTION SPEED ZERO
EJECTION WEIGHT 337 lb,
DUMMY WEIGHT 146 lb. (3%)
TIME TO CHUTE 5.3 sec.
INFLATION
1
50 100
HORIZ. DIST. (FEET)
FigHft 23^6. f^i^ectftPl^ibf Martin-Baker MK lOB
ejection seat at zero speed/zero altitude
(Courtesy of Martin-Baker Aircraft Co. Ltd.).
Figure 23-7. North American HS-1 A ejection seat
(Courtei^ of North American RocfcweB).
23-9
U.S. Naval Flj^t SuigeonV Manual
80,000
100 200 300
165 235
700
aoo
Equivalent Airspeed (Knots)
Figure 23-8. RA-5C escape seat system (HS-IA) operational envelope
(Courte^ of North Ameri(»n Rockwell).
Pre-ejection
Pre-ejectioM is iJiat period of time from initial aircraft damage until ejection is initiated.
During takeoff and landing, and in some combat emergiencies, this period can be quite short and
does not allow for any real preparation prior to egress. During non-combat and some combat
in-flight emergencies, this time often is sufficient for the aviator to do things to increase the
probability of successful ejection. Speed can be reduced and/or sacrificed for altitude, landing
terrain selected, emergency communications initiated, and search and rescue forces alerted. The
aircrewman should iiaiure that helmet straps are secure, the visor down, and the oxygen mask
tight. An harness straps Aould be tightened, and any loose equipment properly stowed. Just
prior to ejection, the pilot should try to insure that tbe aircraft is straight atid level. If the
aircraft is rolling and near the ground, he should attempt to eject when the plane is coming
upright. Body position is extremely important. The body should be erect with buttocks against
the backrest, head firmly against the headrest, and thighs against the seat pan. Figure 23-9 is an
lin^gency Bsciipe From Aiici^
example of of ft-acture which can occur when a pilot ejects with one leg raised off the
seat pan.
Figure 23-9. Leg fracture caused by leg being
slighdy raised off seat pan during seat ejection.
X-ray from repatriated prisoner of war. A-7
aircraft Souti^east Asia conflict. ..
While the time delay prior to ejection can be used to optimize ejection conditions, it can
ako result in unnecessary fatahties. Zeller (1955) showed that over one-third of the aircrewmen
fatally injured during ejection experienced the emergency at an altitude srffifeient'tief '©^^^
good probabiUty of successful ejection, but for various reasons, waited until ihe sdrer*Ft wsS
below a safe ejection altitude b^ore mitiating ejection. , . • - • /i>
During combat operations, the pre-ejection period is extremely critical. Combat pre-ejection
injuries are often severe and include disabUng wounds from shrapnel, intense burns, and smoke
inhalation from cockpit fires. Damage to the aircraft is often catastrophic, with little chance of
23-11
U.S. NwaJ Bli^t Sui^eon's Manual
control, and the aircraft may be disintegrating. If the akcraft is flyable, every attempt is usually
made to reach friendly territory. This may result in delaying the ejection until the aircraft is
euteide the safe escape envelope.
Dynamics of Ejection
Two firing methods are used to initiate ejection in Navy aircraft, an upper face curtain and a
lower D-Ring. Use of the face curtain actuator involves puUing a curtain from over the head and
down over the crewman's, heftd 8tid face. This action fires iie seat catapult. Using the face
curtain aids in correct body positioiBng, |n5d»tects the head against windblast, and helps prevent
the loss of helmet and oxygen mask. Holding the curtain firmly also supports some of the
weight of the shoulder girdle.
With certain types of injuries, and also under high-G conditions, using the face curtain may
be almost impossible. Approximately one-third of the Navy aurcrewmen who ejected during
Southeast Asia combat opertions used^e ieeondarf gea^t pan handle {Every & Parker, 1977).
The force required to pull the face curtain should be 60 (±10) pounds. The force required to
pull the lower ejection handle from its receptacle should not exceed 45 pounds. However, tests
on aircraft have shown considerable deviation from these figures.
The force which propels the Mat%dm the aircraft pl^iduc^s art acceleration ranging roughly
between 12 and 20 G. Many factors, however, will influence the attual value which a catapult
will give for a specific ejection. Propulsion devices are affected by temperature, the total wei^t
of the man-seat assembly (which varies with differences in personnel, equipment, and clothing
worn), the airspeed at time of ejection, the altitude (air density) of ejection, and aircraft
attitude at firing. All will cause variation in the ejection forces actually encountered.
Even though a catapult operates within stated limits, the acceleration forces operating on an
aviator may exceed those of the catapult. This is due to the complex mechanical behavior of
various parts of the body in relation to each other and the relation of the body to the seat when
tiie man-seat system is subjected to ejection forces. The man-seat system is a complex
mechanical system of rigid and semirigid masses connected by elastic elements. When the
ballistic fjQrce is applied, internal interactions cause time lags as elastic elements absorb energy
and then bottom out while the compression forces are still acting. This causes higher peaks of
acceleration which are sometimes called "dynamic overshoots."
23-12
ImeTgeiicy Escape Ftoni Aircr&ft:
Human TQte^4l^]lMti. • :■„ ' ' . !m
Stapp piSS) reported expesures of a human subject to 30 and 33 G at a rate of onset of
500 G per second. In these encounters, which were under ideally controlled conditions, the
objective was to demonstrate simply that such high forces were survivable. Under more realistic
conditions, it has been demonstrated that peak loads of up to 20 and §1 G (Sail b© tolerated
safely during ejea#olB if Ihese Isads are parallel to the 'verttlr* wteiom.
decrea^ japiilf, secflttdaaey to torqpe e^^j ii iim s^t TO(aipfflrrf# not adeqaoEelf^itesteaisWdf
and thj3;vferiitei* cohiitek of the thrust aAip£apJ», 1974).
Vertebral Injuries
Proper body position while actuating the firing mechanism is quite important. Good
position will prevent forward arching of the head and trunk, which in turn will preclude
excessive stress on the anterior portions of the vertebi-ae. Vertebral fractupfes oGCUrring during
ejectidfr*Uave Mcoiiie a frequent injury fA' aircraft escape. Causal factors associated with these
injuries include improper position of tlie body at time of e;^etion, varied tension of the restraint
harness, inverted or negative G flight conditions at time of ejection, improper seat and seat back
cushioning, offset between body center of gravity and the upward and backward (approxi-
mately 18° from vertical) thrust Une of the catapult, and through-the -canopy ejection.
The inort '^ji^eral)le pM:t of iJie spmsd eoluinn is the region around the eleventh and twelfth
thoracic vertebrae. The forward bending movement during ejection is accentuated by the fact
that the center of gravity of the head, and torso is considerably anterior to the s|jm^ ]^toe
(Nutt£ill, 1971). ■ ^' ^ '1'
Because of the likelihood of spinal injury during escape, it is recommended that special
attention be given to the X-ray examinations of aviators who might fly high-performanee
aircraft. These exams would hopefeilly 4MmMs individuals with vertebral injuries at
malfunctions who would be likely candidates fQii(|pnak!NW*y should an emergency escape
become necessary. Rotondo (1975) stresses the importance of a radiological examination
following an ejection. Careful attention to this exam is necessary both for immediate diagnosis
and treatment purposes and also for detection of any latent degenerative changes >vhich mi^t
later affect the aircrewman's safety.
Dynpa^ Overshoot Effects
Dynamic overshoot, discussed earlier for seat components, also occurs within the body. If
the time-force characteristics of acceleration and the decay rate are in harmonic resonance with
the natural frequency of the man-seat system, severe overshoots can be produced within the
body. Latham (1957), in a study of body ballistics using various types of seat cushions, found
28-13
U.S. Na^al Flight Surgieon's Maiia^
that accelerations of less than 0.2 seconds duration and applied at a 400 G per second r^te of
change can produce a maximum acceleration overshoot in the body, A d^t i^angs in the
acceleration period, even 0.03 or 0.04 seconds, will result in a minimuin over^ot condttiofl-
Early ejectic« seat experience indicates the importance of the overshoot factor. Subjects
using diick elastic seat cushions suffered injuries more severe than would kme been expected
from accelerometer data taken from tiie ^at proper. InstrUmeirtation of anthropometric
dummies, which do not have the same internal dynamics as the human body, revealed that the
cushioning caused extreme levels of dynamic overshoot. Upon ejection, the resilient seat
cushion readily compresses, and the seat is well on its way before the man has started upward,
yet aie fmd velocity of man^at assembly is the same. The man then has been accelerated to
pea^ veloerty in a shorter time period than the seat assembly, resulting in both a peater
acceleration and a greater rate of G onset in the man. Fli^t crews dipuld be cmtipned not to
improvise equipment which might appear to provide more comfort (or improve dlting position),
since the unauthorized and seemingly unimportant item rai^t well cause serious injury in event
of ejection.
dyerehoot eWecte can fee partieuiarly severe on intemal organs, , which have fiheir oym
dynamic response to catapult forces. Krefft (1974) discusses tiie various forc^ and stresses
imposed on the internal organs during escape. These organs may be subject to severe
deformation and tensile stresses. During ejection, the vertical acceleration forces may combine
wiih the transverse shock from the ram air pressure. This transverse jolt against the thorax is
immediately transmitted to the heart at its location at the anterior internal chest wall. Here, the
shock leads to a compression where hemodynamic forces exceed the elasticity module of the
tissue, and ruptures may be sustained because of local oversti^tching.
Aiistreion Entry
The accelerations imposed on the spinal column dnring e^etiticcn represent only one of
several stresses to which an aviator is exposed in a short time. Within milliseconds of receiving
the ejection gun acceleration, he enters the airstream, not as a sudden total exposure, but as a
ri^ifiely gradual partial exposure. As the ejection seat emerges from the cockpit, there is a
marked differential pressure exerted on the part of the body exposed to windblast as compared
with the part still protected. While this differential ram air pressure exists only for a very short
period, nevertheless, it does exist and can be the cause of serious or fatal injury. In Some
instances, initial exposure of the helmeted head to the windblast has caused the helmet to act as
a sail, causing fracture of the hyoid bone as the helmet chinstrap is suddenly impacted against it
To mnnmize- this^'di^erential pressure effect, the helmet, oxygen mask, oxygen mask
23-14
Emergency Escapeifioni iAarcraft
suspension, minireg, oxy^n hose, and helmet visor are designed and tested for aMMty to
withstand windblast.
In a few recent accidents, the question of helmet rotation (around the axis of fte chinstrap
attachment bolts) during exposure to windblast has been raised. It has been suggested that if
such i-otation occurred, one^uld expect to find posterior fraetijires of cervieal>»^tebrae, tvith
or without cord injury. Sudi injuries have been noted in isolated instances, but may have been
due to other causes. The problem may or tnay not exist.
Windblast
After the initial +0^, acceleration of the gun, and the differential acceleration of
"gradual" entry into windblast, the entire body and seat combination is subjected to
-Gx deceleration due to ram air force from windblast. This force (Q-force) is proportional to flie
surface area of the man^seat combination and the differential velocity of the man-seat
cowbinatott and the air itt which it moves. Thus, both the airspeed and altitude at time of
ejection are important variables. The higher the airspeed and the lower the altitude, the greater
wiU be the ram air force (Q-force) appHed to the man-seat combination. For all practical
purposes, the pressure (stated in pounds per square foot or Newtons per square meter) is the
density of the air (in slugs per cubic foot or kUograms per square meter) times the velocity of
the air (in feet or meters per second), squared. Q-forces are thus related to indicated airspeed
rather than true airspeed. The following formula expresses Q-force versus speed. .Tins
relationship, expressed in metric units, is graphed in Figure 23-10.
Q = dynamic air pressure in Kewtsfas/met^ (N/m^) i
p =s «ir density in kg/m^ ......
V = velocity in m/second
The important fact to note is that the Q-force increases as the square of velocity. Therefore,
when possible, pilots should nose up, their aircraft prior to ejection to reduce airspeed and
increase altitude.
Abnjpt entry into the tarsti^it^ speed causes formidable stresses. For example, at an
altitude of 5,000 feet and a true airspeed of 600 knots (.9 Mach), the ram air pressure
encountered is 1,240 pounds per square foot. This means that a man presenting approximately
6 square feet of frontal area will receive a total ram air pressure (Q-force) of 7,440 pounds or
approximately three and one-half tons oi ram air presstt^s ■ ■
23-15
U.S. Naral FU^t Stn^onV Maniud
200 400 6O0 800
SPEED (KIAS)
Figure 23-10. Dynamic air pressure vs. airspeed
(Ring, Brinkley, & Noyes, 1975).
It is important to note that it is not Q-force per se which causes the major injuries associated
with high-speed ejection. Payne (1975) cites examples of persons exposed from 4.8 x 10^ N/m^
to 14.4 X 10* N/m^ withdiil seiious injury. Hiere are, howevef, two ctiitikictive injury patterns
associated with higher Q-forces. TRe ISrst, gB«#idly leifeffied M m teiig 'Windblast, normally
results in only minor injury to soft tissue. The second type, commonly referred to as flail injury,
results from the summation of forces over larger areas producing differential decelerations of an
extremity rcllftive td ihe torso and seat (Ring, Brinkley, & Noyes, 1975).
Glaister (1965) states that the different effects of Q-forces can be divided into those
produced by windblast, whiiSh result in in|iifies as petecM^ and subconjunctival
hemorrhage, and those produced by flaiHng of the head and ^xtreMties; Heal flisafing cause
unconsciousness or fatal brain damage, while flailing of tibie Wms and legs can lead to fractures
(generally the consequence of impacting seat elements) or joint dislocations. When the body is
unsupported, a Q-force of approximately 3 x 10* N/m"^ or more can lead to flailing that cannot
be controlled by muscular effort. The onset of flailing can be so rapid tiiat muscular reflex
action is ineffective, even at Q-values belOW 3 x 10* N/m^. At Q-values of 3.7 x 10* N/m^, full
abduction of the hip joints can take place in one-tenth second; at greater Q-values, the loads of
unsupported limbs may exceed the strength of the major joints.
Another factor, sometimes termed "windblast erosion," is the effect of the air pressure on
protective clothing and equipment. In the past, clothing has been torn, shoes pulled from the
feet, helmet visors shattered, helmets lost, and parachutes prematurely deployed, the last
usually with fatal results.
From experience gA^ed ifi #ind tunnel and rocket sled tests, survivor accounts, and Medical
Officer Reports, many improvements have been made to enhance the integrity of personal flight
and survival equipment. for high-speed, low-altitude ejection. This underlines the importance of
adequate accident reporting, even in cases where the loss or malfunction of an item of
equipment was not a direct cause of injury.
23^16
E<liter!gen&y E^eape From Aircraft
For certain comLmatiOriS of i^speed and altitude, the deceleration forces encountered
during high-speed escape can be greater than those encountered during a crash where the
aircraft collides with ground or water. The duration of the G-forces may in fact be 10 to
20 times greater than that experienced during a crash situation.
When a condition of random tumbUng or spinning exists, the pattern of mechanical forces
acting on the body becouies^^e^ttemely complex, ahnost befQiid i^oitteaiplation, let alone
computation. ' y
Goodrich (1956) has calculated the relationship of caUbrsttid airspeed, altitude, and Mach
number to deceleration force (Figure 23-11). The calculatjcfiW'tre based on a stable seat system
with no tumbling or spinning. The values shown are for one seat system and should not be
considered as absolute values. For any particular system, the foUowing factors affect the rate of
onset, peak G, and duration of deceleration:
V — Velocity at time of ejection
P — Air density ' : : '
A — Frontal area exposed to airstream
W — Weight of the ejected mass (man and seat)
Cd - Coefficient of drag of tke occupied seat
t
LU
LL
111
Q
H
<
60
50
40
30
20
10
20G
l\
I\
30G
.t >v
'v'
40G
G
60 G
\j
i >
SAMPLE a
\LCULATION-\
1/2 PV ^
M
pi
rrs
w
A= 6.5 FT. SQ.
W= 325 LB.
\ 1
200 . 300 40e 500 60O 800 UOOO
.„ . ,. ,. .,<^^yipTiP AIRSPEED (KNOTS)
!l ; Figure 2MI. iMiipiWdt#6-&B^ as a function of altitude, caBln-a^
and NJacb number (Goodrich, 1956). ^.^ ,»„,,.
Tlie rftifatioti of iiie '^^^^ force is dependent on air density. The deceleration period
increases with an increase in altitude. At 40,000 feet, the deceleration period will be
approximately twice that experienced at sea level air density. Figure 23-12 shows this
relationship. " "
23-17
U.S. Nsral Fti^t Sui^on'e Mmiul
50
.5 1.0 1.5 2.0 2.5 3.0
TIME (SECONDS)
Figure 23-12. E£Eect of altitude on deceleration time
(Goodrich, 1956).
Litnb Flail
During high-speed ejection, it is the "differential deceleration" of the extremities relative to
die torso and seat which is the primary cause of extremity flails Midi iaj&tf occurs because the
arm(s) or leg(8), after having broken away from their "stowed*' or initial positions, build up a
substantial velocity relative to the torso and seat before reaching a "stop." This "stop" may be
part of the seat structure, the limit of travel of a joint, or a combination of both. At high
speeds, the "stop" is encountered with such force that bone or joint fracture results (Payne,
1975).
The high percentage of extremity flail injury found with combat escape in Southeast Asia
was closely related to ejection speed. Almost 50 percent of the Southeast Asia combat ejections
were above 400 KJAS as compared to only 5 percent for non-combat ejections occurring during
fliis same time period (Figufe 234 S). Hie correlation between high-speed ejection and flail is
readily apparent when these speeds are plotted against frequency of flail injuries (Figure 23-14).
The use of extremity restraints is one of the best solutions for preventing flail with open
ejection seats. Aircrewmen, however, are not always willing to wear the restraints, especially
those for the upper extremities. Alternatives, which include passive entrapment nets, require
that the seat fly stably and be pointing in the direction in which it is traveling. The grasping of
the face curtain provides some relief from total arm flailing. However, there have been instances
of elbows moving outward and away from the trunk. This "butterflying" has caused both arm
and shoulder injuries.
23-18
Emergency Escape From Aircraft
LEGEND
Combat Data
Operational (Non^mbat) Data
SPEED tKI.AS)
F^ure 23-13. Combat vs. operational eiection^>eedd'^|!!^ & Parker, 1977).
PERCENT
FLAIL
INJURY
1~ 1 1 1 r
0-93 100-199 200-299 300-399 400499 500-599 600
EJECTION SPEED (KIAS)
Fi^re 23-14. Incidence of major ilail injury vs. ejection speed (Every & Paiker, 1977).
23-19
U.S. Naval fli^t Surgeoii's Manual
Temperature Exposure
Accident experience with ejection systems indicates that exposure to low ambient
temperature is of httle significance as long as standard protective flight clothing is worn, and
iteios of equipment are neither damaged nor lost during escape.
The hi^ temperatures which ean be caused by the ram rise effect at hypersonic speed have
not been experienced as yet in emergency ejections. Aerodynamic heating is certainly a factor
during the reentry phase of spacecraft operation. At high Mach numbers, the temperature rise is
very severe, approximately 75 times the square of the Mach number (for Fahrenheit scale). This
is compounded by the low heat-exchange factor which exists in flie rarified higher altitudes.
^indblast tests of lajrge animals (chimpanzees) on high-speed rocket sleds have produced
severe third-degree bums on exposed body areas. These tests were conducted at a Mach number
of 1.7 with a total windblast exposure of 10 seconds (during acceleration and decay of the sled)
and exposure of 1 second at peak velocity. Measured surface temperatures were 300° to
320° F, but these alone would not have accounted ftjr the injuries. The total transfer of heat
due to the hi^ airstream velocity was noted as the causal factor (Nuttall, 1971).
It is doubtful that current open ejection seat systems will be used in hypersonic vehicles.
Rather, some form of closed escape module will be used to counter thermal and other factors.
Tumbling or Rotational Stress
The head-over-heels tumbling which can occur while an aviator is stiU attached to the seat is
dosely associated with the problems of windblast and wind-drag deceleration. Tumbhng is
particularly hazardous at high altitudes where combinations of tumbling and spinning in all
degrees of freedom of rotation can occur. Walchner (1958) conducted dummy drops from
83,000 feet which indicated that the human body may develop a spin rate as high as 465 rpm,
Weiss, Edelberg, Charland, and Rosenbaum (1954) utilized a spin table to investigate animal and
human reactions in order to establish tolerance Kmits. These tests showed that with the center
of rotation at the heart, unconsciousness occurred in humans in 3 to 10 seconds at 160 rpm.
Indications axe tfiat s^ia rates of more than 400 rpm are fatal to man (U.S. Naval Fhght
Surgeon's Manual, 1968).
It is beheved that the fatal rate of 400 rpm can be attained during free fall. Navy accident
experience does not indicate that this has been a problem in emergency escape to date. This is
attributed to the infrequent occurrence of hi^-altitude high-sfteed.escape events.
23-20
Emeirgemcy Esc^^e From Aircraft
Walchner (1958) reported actual tumbling and spinning experiences of parachutists with
rates as high as 240 rpm. This would produce a radial acceleration force of approximately 37 G
at eye level, which would be capable of producing severe retinal or cerebrovascular damage.
Spiniung and tttnab1|ag.^»^' Giiuse a combination of positive ah^ negaiiv& ieJM^MtliFB^ II^e
effects of which will vary with the location of the center of rotation. When the heart is the
rotational center, cardiodynamic and general circulatory effects are maximal. Animal studies
have shown that at 150 rpm, with the heart the center of rotation, the A-V pressure difference
and puke pressure are reduced to less than 5 millimeters of mercury, and cardiac output is nil,
lH'toB ano^a 'tfeB#&, tet'*6ei#^tf1tiiW0W*fei#'' damaged v^diiiilr'Witi' W'dccur as
spioumg ceases and very h]^ systofiic Mood pressure overshooting occurs. CirculatoKy
impairment is not serious in hiintans at 125 rpm. * - " ■ : '
Hydraulic effects are greatest at those regions which are farthest from the center of rotation.
When the center of rotation is located at the lower part of the body, conjunctival hemorrhage,
periorMtid ed^ma, and hemorrhage into the sinuses and middle ear may occur. The thresholds ei
petechial hemorrhage o| fhe Gdnjititctiva hme been determined. With the center of rotation at
the iliac crest, the fife^ from 3 seconds at 90 rpm to 2 minutes at 50 rpm. With the center
at the heart, the ranges are from 4 seconds at 120 rpm to 10 minutes. jit 45 rpm (U.S. Naval
FU^t Surgeon's Manual, 1968).
Ejection seat
[ hm becoiae a less serious problem due to #e eiEeftiveneE^ @{
stabilizer drogue ehBlestj^ri^e'^aoie^iifts^ Ito rocket thrusters, which
compensate for misalignment md tend to prevent tumbUng alid uncontrolled. spinning.
' •JPflradlute Descent and Landing -j
The Parachute
AH escape systems use a parachute to lower aviators to the surface sit a safe vertical velocity.
In referring to parachutes, the alphaiH^pu^e dfpgi^tion of tiie assembly is used, such as NB-7.
The pack typ^ ^back, ,|eat^. ©^, cjl?^p8i) may be noted. The canopy size and shape may also be
mentioned in terms of diamet^ Wf the canopy skirt (28-foot flat or 26-foot conical). Personnel
parachutes consist of three primary parts: canopy, pack, and harness. Supplementary parts may
include internal pilot chute, external pilot chute, and/or a spreader gun.
All personnel paraehiui^ta^#ilk8Wtdte)i^|>^ap|ti^^^ (the-ftik^t chute) attaehgd ^liie Igjiilif
the mam .parachute ciwopy. It deploys, first, bt^pg forcibly opened by a wire spring assembly,
and extracts the maiii eauopy. This assures rapid, predictable deployment of the main canopy
23-21
U.S. Naval Fli^t Surgeon's Manual
and causes the suspension lines to be partially tensioned prior to the application of main
canopy-opening forces. Parachute deployment may be accelerated by drogue chute extraction.
At low airspeeds, the rate of main parachute canopy iailation ean be inoreased tlu'ou^ the use
of a ballistic spreader gun, which, in effect, is a powered, positive chute-opening device providing
forced symmetrical opening of the main parachute canopy.
A Flight Surgeon can familiarize himself with the specific parachute assemblies in use by his
unit throu^ visits |d the pflrachute loft. Parachute risers generally are; well aware of their
responsibilities, wdl versed in the capabilities and limitotiojis of survival/safety equipment, and
are willing to discuss equipment items with interested personnel and to demonstrate their use.
Parachute Opening and Descent
Parachute-opening shock can be severe if escape conditions are such that the drogue
parachute either malfunctions or the main parachute deploys prematurely. Figure 23-15 shows
the relationship of opening shock versus airspeed for a 28-foot canopy.
,1- i
25
^ 20
B
M 15
O
Z
z 10
HI
a.
O
5
0.
0 100 200 300 400
A*R®»EED (KNOfSJ
Figure 23<I5. (Wci|iy opening shock vis. ainpeed for 28^
(Irom U& iVtwiil It^r Si^^
High-altitude seat/man separation is relatively rare with today's ejection systems. However,
if it does occur, additional hazardous factors are introduced. Temiinal velocity increases at
Mtitude, with the result that parachute-opening shock is generally increased to a point where
damage to the parachute structure and/or injury to the airman tAtcy result. The M^er altitudes
also expose the individual to a low partiitt pressure of oxygen and low temperatures.
23-22
MAXIMUM
PERFORMANCE
Emergency Escape From Aircraft
The problem of an increased parachute-opening shock is the most important of these
factors. As altitude increases, air density decreases, and terminal velocity itself increases.
Terminal v@k>@ity is dependent upon Ijie ratio of aerodyiiainj^,^^>to th&wei^of :^e. {ailing
body. Aerodynamic drag is a function of air density. Therefo|^j, at higher altitudes, the falling
body falls at a faster rate to create an air drag equal to tiie weight of the body. Two other
factors induce increased opening forces at higher altitudes. During parachute deployment, the
drag created by the "streaming" chute is less; thus, a smaller deceleration force is appHed. In
addition, the increased rate of air flow and the reduced resistance to opening caused by low air
density cause a more rapid deployment and inflation of the canopy. The overall effect is
significant, and aircrew personnel should be familiar with the consequences of high-altitude
parachute actuation. Figure 23-16 shows the relationship of altitudie' afll pSSfachute-opening
shockitthetermindveloieityof toavetiigewei^taircrewman, ••
0 5 10 15 20 '25 30
, . , OPENING SHOCK (G) \
Figure 23-16. Parachute opening shock in relation to deployment Stitudc
at terminal vdocity of man (28-foot canopy) ' " ' -
(from U.S, Nawd Flif^tSurgeon't Manmd, 1968).
High-speed parachute-opening tests (200-300 KEAS) were conducted to determine
parachute system mte^iy md the effects of acceleration and openmg-shock levels with regard
to human injury (Dahnke, Palmer, & Ewmg, 1976). These results showed that hi^-speed
23-23
U.S. Naval Fli^t Surgeon's Manual
parachute opening can produce catastrophic damage to the canopy. In addition to canopy
damage, a number of other parachute system problems were encountered. The windblast
integrity of all systfems felt' liiuch tb be desired. This Wte evidenced byi:^lt ItttlMttg out of €le
ftajefcj'eJEtsrasivid'paek rilotioii due to windblast, failure of the pack interface attachment to the
survival Wt, and rifi^ira Mown down over the Bhoiijd
High-Altitude Problems
Problems of hypoxia during high-altitude escape should only occur if, for some reason, the
emergency oxygen supply in the escape system malfunctions, or the oxygen mask is damaged or
lost during escape. Probleing witil hypoxia aJfe^coveredijBLffe^siotogy' o/fZ^ftf. Protective flight
clothing is generally adequate to protect agsfast A-ostbite at hi^ altitudes. Use of gloves is
especially important, however, since finger dexterity plays an important role durmg parachute
landing and postlanding survival activities. Disorientation and confusion may result from
tumbling and spinning during descent. The primary problem resulting from this spinning is the
increased likeUhood of severe parachute entanglement during main chute deployment.
Vertical Descent Velocity
The vertical velocity at which the canopy lowers the airman is ffssentidly a function of
fabric porosity, canopy size, and integrity. The larger the canopy diameter, the lower the
landing velocity, as modified, of course, by the air density changes with descent. Table 23-2
indicates the rates of descent at sea level for various parachute canopies and for various
man/equipment weights. The rates of descent can be equated practically to the equivalent of
jumping from heights of 3 to 10-^ feet onto solid ground.
Table 23-2
Rate of Descent at Sea Level for Various Size Parachute Canopies
and Man/Equipment Weights
Canopy Size (Diameter) in Feet and Designation
Man/Equipment Weight
24' IWartin-Baker-
Rate of Descent
26' NB-6-
Rate of Descent
28' NB-7,8,9-
Rate of Descent
280 lbs
25ft/wc
22 ft/sec
250 M
22 n/set
160 lbs
20ft/s8e
18.5 ft/sac
17.5 ft/sec
IU.S. Navti FU^t Suiyeon 's Manual, 1 968) .
23-24
Emergency Escape From Aircraft
n
Parachute-opening accelerations also vary as a function of canopy diameter, but not in the
way one would normally assume. Smaller canopies impart a greater G-loading during opening
than do larger ones. Thelat^r canopy, upon deployment, stteltosheMnd; the aviator, creating a
loss of momentum, and takes a longer periad of time to inflate than does a smaller eancrpy:. *^e
smaller canopy reduces momentum to a lesser degree and inflates inore j^piffly. The differeno^^
in momentum reduction and filling time account for the greater ftcceleration impasted by the
smaller canopy.
•■ 4' ' ' <
Parachute Landing
The airman performing an emergency parachute landing does not have the luxury of
selecting his landing site, weatl^er coJiditions, and the like. He may be landing in mountainous
terrain where high rates of descent and hardeMandings wiU be experieiiced, along with updrafts
and downdrafts. He may be landing at night which predud«» seeing laMifflr% hazards. In addition^
he may be landing with high surface winds which impart a horizontal velocity during WiMb'^
and may cause him to be draped across the ground or water.
The proper prdawtog posiiibn is mmdatoiy if injury is to Ife TfiflMllniased. Where altitude
permits, the prelandihg position shoxild be assumed at an altitude of 1,000 feet above ground
level. Both arms should be outstretched above the head with the hands firmly grasping ^e
^ ^ risers. The knees should be slightly bent and the feet held together (not crossed). The jumper
should direct his view at a 45-degree angle to the ground. This line of vision will prevent
anticipation of surface contact and the retraction of legs which becomes almost an involuntary
act if '-the jumper looks strai^t down. Statisties ctunefeVning night' latotBto^ li!Sffcate that the
chances of injury are less than during dayhght hours. This may be due to the fact that the
landing impact cantlbt be aiiticip^tted, and le^ jtlill^pato|y ten^Hg ftitd leg reteaction occurs.
Water landings present additional hazards. Drowning from dragging or parachute
entanglement is a major problem and can happen to the best of swimmers even with relatively
light surface winds. Since it is extreiilely dif-ficult to judge height above water, rio attempt
should be made to release from ttie fedrnesfe just prior t© l^tdiiMg. fte aiiWlwi itWift tilease
canopy fittings immediately upon entering the water or shed iiie en^e karnese assembly. The
in-water entanglement problem proved especially severe during the Southeast Asia conflict
where a large number of aircrewmen came down over water or flooded rice paddies, either
severely injured or unconscious {Every & Parker, 1976).
Ejection Accident Summaries
Navy non-combat ejection survival percentages for the past 10 years, presented in
Figure 23-17, show a continuing rate of success (non-fatal) of 80 percent or better, approaching
■ )
23-25
. II.S. Naval Fti^t Sntgeon's Mtmiial
§0 percent at times. The extent of injuries encountered during the last 5 years in these ejections
is shown in Figure 23-18. The causal factors responsible for the fatahties over this same time
period are presented in Figure 23-19.
EJECTION SURVIVAL PERCENTAGES
90 , ; , , ; ; ; ; , ; ,
781 1 1 I I I 1 1 1 1 1
t965 1967 1969 1971 1973 1975
CALENDAR YEAR ■
Figure 23-17. Naval Safety Center 1975 Emergency Airborne Escape Sunuaary
(non-combat clatt only).
Low^titU'de, low-speed (out of the envelope) ejections are responsible for many fatal and
major injuries in non-combat ejections. During combat ejections, almost 60 percent of major
iniuries are sustained during high-speed ejection. A comparison of non-fatai escape injuries for
these two groups is presented in Table 23-3. The probable primary causes of known combat
escape injuries are shown in Table 23-4.
Pattern of Ejection Injuries
Preceding sections discussed injury causation as related to specific events associated with
leaving a disabled aircraft both in combat and non-combat circumstances. The pattern of
injuries likely to be produced by emergency escape is somewhat unique and should be
recognized aS such by the examining Fligjit Surgeon. There are certain injuries which could well
be overlooked if the examiner is not sensitive to the circumstances of escape and the particular
forces that are apphed to the aviator. Table 23-5 is presented as an overview of injury patterns
which may result from aircraft escape and summarizes the events producing these injuries. It
should be of some value to a Fli^t Sui^eon as he dievelops a set of procedures to be used when
a recovered aviator is examined.
23-26
EJECrfON INJURIES
CY I97I-I975
70
«0
lifl W3 1974 1975
CAffiWAR YEAR
Figure Naval Safety Center 1975
Emergeocy AiAome Escape Summary,
(non-corabat data only)
EJECTION FATAUmS-CAiJSAL FACTORS*
CY W70-mS
•0
70
60
50
40
30
20
10
V
■ *i
»970 W7I 1972 W73
CALENDAR l^ilit
HiTf
our OF SEAT ENVeiOPC
AlAlEtlNCTfON OF XAf/CMW SYSTEM (IMCltPIVIG
i-KodPOUBES OR mA»m0m*cs imm$)
iNJUl^ DURmd ACeiOit^/EpCTlON OR
AFTER EJfCTJON-NO AFf^^T SYSFEMS MAIFUNCTION
DROWN£0/PROBAUy|>jKMVf«D
FtREBAU/EXnOSION
DEUY IH IWTIAriOH OF EJECTION
Figure 23-19. Naval Safety Center 1973
Emergency Airborne Escape Summary,
(non-ccunbat data c»%)
U.S. Naval Fli^t Smrgeon 's Manual
Tabl© 23-3
Non-Fatal Escape CojSiJjariaDn for Period
During Southeast Asia Conflict (196(5-1972)
Injury
'
Major
Minor
None
Navy Combat
40%
30%
30%
Navy Non-Combat
19%
37%
44%
(From combat data. Every & Parker, 1977)
Table 23-4
Probable Cause of Known Combat Injury
Percent
Flail
Enemy Inflicted
17
Ejection Seat G -Forces
14
Struck Object
13
Parachute Landing
11
Fire
10
Parachute-Opening Shock
2
(Every & Parker, 1976)
Special Eseape Problems
Previous discussion has centered abottt escape from fixed-'Wing jet aircraft. Additional
problems are encountered with escape from rotary-wing aircraft, V/STOL aircraft, and in
underwater escape.
Rotary-Winged Aircraft
Helicopters have unique problems of escape. If engine failure should occur above a
minimum altitude (usually around 400 feet), there is less danger because the pilot can initiate
autorotation loid make a safe desdent. If, on the other hand, engine failure occurs below a
maximiun altitude (usually 30-40 feet), the helicopter can land without killing anyone even if it
drops like a stone. The "danger altitude," therefore, is rou^y below 400 feet and above
23-28
Table 23-5
Overview of Ejection Injuries
Time
Pre-eiection
Ejection
Cause
Fire in cockpit
Explosion
Negative G
Ejection seat G forces
Struck by seat or cock-
pit object
I mpact canopy
structures
(a) Windblast
(b) Helmet rotation
(c) Hail and rain
Irijury
Burns and smoke inhalation.
Blindness.
Wide range from lacerations
to multiple Extreme.
Head or neck strain. Cervical
fracture.
Spinal compression fracture.
Extremity fractures and/or
Isiqieiati^, Footfractures,
especially toes.
Severe lacerations. Neck
strains. Spinal compression
fractures. Hem^ietmasi
Petechial, conjunctival, afid
retinal liemorrhages.
Neck strain.
Contusions. Hemorrhages.
Comment
Possible Severe li«lrh to exposed areas; espfdaWy If sleeves
rolled up and gloves not worn.
Most commonly found during combat, however, may be
caused by internal explosions or premature detonation of
ordinance.
Pushed up against cockpit from Negative G.
Most vulnerable area of the spinal column is from T-10 to
L-2. Primary cause is out of proper ejection position, other
contributing factors poor design of seat, type inmiiffir
charge, and space between seat and buttocks. Post-ejection
physical should include radiological exam of entire spinal
column.
Fracture of femur from leg being raised off «at during
ejection. Striking cockpit or seat structure. RIO's and
RAN's striking electronics equipment.
Especially prevalent in thru-the-canopy ejections.
PaMieuJarly A-6iiftd A-7 A/C. Contusion and hematoma
injuries from striking canopy support structure parts.
Direct effect of windblast to exposed area.
High-speed wind effect under helmet possibly can produce
severe stress to neck muscles and cervical vertebrae area.
Rain and hailstones will cause severe injury to unprotected
parts of the body at speeds in excess of 400-450 knots.
In
Vietnam combat, 20 percent of the major injuries received by aviators occurred prior to ejection.
Table 23-5 (Continued)
Overview of Ejection Injuries
Time
Cause
Injury
Comment
Election
(Continued)
Flail (linear decelera-
tion)
Fractures. Dislocations of
upper extremit^s, predom-
inately to elbow, upper arm,
and shoulder area. Torn
tisaments and dlisTocatiOn of
lower extremities, predomi-
nately to knee area. Fractures
to tibia and fibula. Cervical
strain.
Most common of the major high-speed escape injuries. Re-
sults from Q-forces produdng dtflerential deceleration of
the extremity relative to the torso and seat. Followed by
a sudden striking of seat structure or reaching the limit
<rf the joiitt. Less prevalent on seats with extremity
res&aint system.
Accelerative and de-
celerafllVefordss
(a) Internal injuries to
body tissues and
organs.
(fo) Uneonsciousness.
The multiple shock-tike forces which act on the aircrewman
during ejection can produce tearing and rupture injuries
to thoracic and abdominal organ& Of special criticality
arp fmrHifif* iniiiripc Pfin^nntipnl^lu a Rsrriinlnciir pvam
QIC ^#a(UIQb II Ij.UI Uwl I^Q^UCI ILiy S -I^OI UIWIU^II^ CACIIII
should be included in all post-ejection physical examina-
tions.
High percentage of unconsciousness during ejection due to
a specific impact or a summation of forces. Some cases
lasting several hours.
Parachute Deploy-
ment
Paraciiute^open ing
shocit
Cervical fracture or strain.
Contusions or severe muscle
cnminc tnrcn rticJrkf^atimn
S^iaillO LU I.UI3U. wlalUUXLIUI 1
of cervical vertebrae. Fracture
thyroid cartilage.
These injuries are intensified by a loose torso harness,
premature parachute opening, and possibly the use of de-
VILrCa LU alU ill (K|tClUlUU7 UC^IUyillCIIL ul tiiOilU^y III 1 Tal-IUlii
Dislocation of cervical vertebrae may be linked with loq«
chin strap.
Riser slap
Facial fractures, contusions,
or lacerations.
Usually from excessive yaw or uneven tension on parachute
risers during canopy inflation. If part of riser harness
catches on the helmet possible cervical fracture could result.
Time
Parnate Descent
Landing
Generai
Cause;
High-altitude ejection
High-speed rotation
and/or spinning
Descenr^rii trees
Landirit.,Miiact
Paradid^drag
Descent in or near fire-
bait
In-water parachute
entanglement
Escape #va^
Injury
Frostbite.
Severe pain. Hemorrhages..
Displacement of limftsv-
Lacerations.
(a) Leg-anklf triMmjra.
(b) Spinal fracture.
Severe drag burns. Fnte^s.
Burns.
Water in lurtgs and stomach.
Shiydt, -
Comment
Severe frostfafle poiaiite to exposed skin following
altitude ejection or very cold climates.
Gjnerally only a problem if stabilizing system on ejection
safaris or at high ittityde.
Parachute descent thru trees can result in severe contusions
and lacerations. frsm *e trees. Parachute damage may also
result in severe lipfu^ tipiries.
Results from improper landing especially on hard or rcHdfti
terrain. Likelihood of this type injury is increased wi^
parachute oscillations during landing. Existing fracrhir^.
may become comminuted at this time.
Usually occurs to lower thoracic, lumbar, or coccyx as a
result of sit-dciwn landings. \"
Severity depends on wind, teeraitt, and tinw before
parachute release.
The frequency of this mishap is greatly increased in-
rfrom V/STOL aircraft.
Quantities of water can be ingested into the lungs or
stomach following parachute landing and entanglement in
open water. "■ '■ z
An aircraft ejection, even under the best of conditions, is
extremely taxing physically as well as mentally. The Flight
Surgeon should watch carefully for signs of shock, even in
what appears to be an injury free escape.
U.S. Naval Flight Surgeon's Mailual
40 feet for singk-engine heliocopters. Within tltm altitude »one, eiipne failure uscially results in
severe injury or death to the aircrew. Naturally, these altitudes vary wi|h tiia ehffftu^tSristics of
the aircraft concerned and are of little concern in twin-engine craft, mice one engine can usually
carry the load and prevent an accident.
An in-fK^t fire, damage 6r loss of main or tail rotor, or engine f ailute (or fuel starvation) at
ni^t, are Occuw-ences which reqiare emergency- escjq)e prior to landit%. Currency, helicopter
crews are provided with conventional personnel parachutes. However, their use has been
minimal due to the low altitude at which escape situations usually occur (below minimum
parachute recovery altitude), and the danger of impacting main rotor blades after egress,
especially if the heUcopter is tumbling inverted. Some proposed methods of extracting
personnel from htSlicopters along with a rating ctf gome of the pToBlemS asso^iated with each of
these methodsjare shown in Figures 23-20 and 23-21 (Melzig & Schmidt, 1973).
V/STOL Aircraft
Vertical takeoff and landing aircraft have the unique problem of requiring an escape system
which will perform at conventional high speeds and high altitudes as well as at low altitudes
with zero horizontal velocity. Ejection experiences with this type aircraft have shown that most
ejections occur at low speeds and low altitudes with the aircraft sinking and/or banked (R^der,
1973). Two specific problems are criticd wi^ this type of ejection; XM Ejection is below ftie
lower altitude hmit of the envelope and migr^revent full parachute deployment before in(pact;
(2) The pdot ejects and descends into his own aircraft's wreckage fireball.
t .*
Underwater Escape
In all of 1975 there was only one successful underwater ejection. This method of escape is
discussed here, however, because naval operations from aircraft carriers present it as a constant
possibility. Manual escape with the help of the life vest is always preferred to ejection, if the
canopy is open or off, when submersion occurs. If the canopy is on joid th&aircraft is sinking,
then it is preferable to eject through the canopy. Oxygen should be breathed until ejection is
initiated and the Ufe vest should be inflated immediately. While ascending to the surface, the
survivor should exhale constantly to avoid an aeroembohsm.
The most critical problem involving underwater escape is the inahiHty of drcrewmen to
escape from a helicopter following an in-water mishap. These mishaps account, by far, for the
greatest loss of life from this type of aircraft accident. Data from the Naval Safety Center show
that over a four-vear period (CY 1969-1972) 78 Navy helicopters were involved in water
accidents. Of the 63 hves that were lost in these accidents, only ten were due to injuries; the rest
of the crewmen, many of whom were last seen stiU in the hehcopter, were dro'toed or lost at
23»^
Emergeniijr EBCape'l'foiii Aircraft
^^^^^
MANUAL BAILOUT
CAPSULE BeepVERiy
T9TAL AIR0RAIif RECOVERY
EXTRACTION, SIDEWARD
EJECTION, SIDEWARD
EJECTION, SIDEWARD-UPWARD
EXTRACTION, UPWARD
■ *—
/
/
EJECTION, UPWARD
0
EJECTION, DOWNWARD
Figure 23^20. Escape measureB for helicop^ra (Mdzig & Schmiclt, 1973).
2. Helicopter Performance Degradation
3. Rotor Disposition Requirement
4. Technical Risk
5. Servicing Factors
6. Hurnon Factors
7. Combat Vulnerability
8. Adaptability for Retrofit
9. Cost (Up to an QperQfjQnal System)
lO'.Time (Up to an Operational System)
c
0
c
u
0
c
ion
out
o
u
u
0
0
■•-
LT
u
X
^
01
'5
LU
M
u?
lU
00
TJ
111
T5
D
a
-D
O
13
0
war
_«
C
01
tj
a
o
a.
a
o
y
in
B
B
io
1. Escape Concept Performance Capability
^ excellent
^ very good
good
(J satisfactory
(3 poor
0 very poor
Figure 23-21. Ranking of escape concepts for important evaluation criteria (Melzig & Schmidt, 1973).
23-33
U.S. Naval Eli^t SiirgeoiL'8 Manual
sea. Descriptions of survivors' escapes verify that in many cases it waB oti^ Inek that saved
them. Panic, disorientation, jammed hatches, entanglement, in-rushing water, and darkness are
words common to almost every scenario.
The lack of any real flotation capability for most Navy helicopters undouhtedly affects the
survivahihty of in-water heHeopter ^rashes. Table 23-6 presents the survival rates for five types
of helicopters now in use by Navy and Marine Corps forees. The H-2 helicopter has one of the
highest fatality rates, with over one-quarter of all personnel involved in H*2 accidents becoming
fatalities. It may be presumed that this fatality rate is in large measure a function of the
neghgible flotation time plus an inabihty for crewmen to escape rapidly while the vehicle is
sinking.
Table 23-6
Survivability of In -Water Helicopter Crashes*
1969-1972
Aircraft
Number
of Accidents
Number of
People Involved
Number of
Fatalities
Percent
Fatalities
Percent
Survivors
H-1
22
90
10
11,1
88.8
H-2
10
42
11
26.2
73.8
H-3
19 I
98
9
9.2
90:8
H-46
19
132
28
21.3
78.7
H-53
1
5
4
80.0
20.0
Total
78
"Adapted from: Underwater Escape from HsIlceiRtsrs. E.V. Rice & J.F. Greear III, NSC. Norfolk, Va. Paper presented at
1973 SAFE symposium.
A number of ways are currentiy being explored to enhance the survivability rates of
helicopter in-water crashes. These include the use of pyrotechnics to create emergency hatches,
better bghting of existing feitches, emergency underwiater breathing systems, and improved
training ecpjipment.
Training
Navy policy does not require aviation personnel to perform actual parachute jumps. Aircrew
personnel are required, however, to undergo certain training in order to learn the proper
techniques and procedures fo( ^ediafg T*i% emergency situations. *
Ejnergency Ground Egress
Ditching and emergency ground egress drills are required in most commands. Even with
high-performance aircraft equipped with zero-zero ejection seats, there are takeoff and landing
23-34
Emeigency Escape Fzom Aircraft
emeEgem«& on flie deeik wlaofe mqiiire split-second decisions as to whether to eject or stay with
the aircraft. Survival rates, however, for on-the-deck emergencies are very similar for both those
who eject and those who choose to remain with the aircraft (Rice & Ninow, 1971).
Hehcopters and propeller au-craft offer a higher probabiUty of on-the-ground e^ess
following an airborne emergency. Consequently, squadrons wi# #08 type of aircraft should be
aware of the importane© of ©iscape drills and should stress, WJs Utilizing primary as well as
secondary escape hatches. Studies of miUtary and commercial aircraft accidents
(Pollard & Klotz, 1971) reveal that most fatahties are not due to crash trauma but to a person's
inabihty to get out of the aircraft. These studies were made using data from fixed-wing aircraft.
However, since heHcopter airframes are generally less substantial, it is expected that structural
damage to hatches would be even greater following heUcopter impact. Drills should be initiated
tathef immediately after crew members have embarked and are strapped in, or immediately
following aircraft parking and engine shut-down. Crews are scored on the basis of following
correct procedures and exiting the aircraft within a prescribed time. Conscientious crews are
able to correct many faulty procedures and considerably shorten abandon time. Records are
normally maintained by the squa^oii sMt(B% cfRmf ot%i ikci^ cbttimanfe to fittstltfe that
drills awl f feld pM^diedly , ind^th^^ esSt ttmes are reasoiiMlfe br improving. The' squadron safety
officer should review military specifications for all aircraft in his squadron to determine egress
times with or without auxiliary equipment which might block a specific egress path. Lectures on
egress should include complications due to fire, smoke, injury, panic, jammed hatches, etc.
These drills are most effective when no forewarning has been given to the crewmembers. At
some activities, the squadron safety officer or his representative will meet an ittriviag Jatc^ii
and give a prearranged signal to the pilot who in torn will announce "emergencf tegress'' or
"ditching driE" to the crew. The total elapsed time is then recorded, and errors and procedures
noted. This permits immediate discussion of problem areas and also serves as an mdication of
eimoim to all eteiW^s.
DUbert Dunker and Helicopter Escape Trainer
The Dilbert Dunker consists of a simulated aircraft cockpit section mounted on rails which
extend into a swimming pool. The trainee, after receiving proper indoctrination, is seated in the
cdfekpflyfill shofdder harness and lap helt seeuiSfed. Thfe feockpit assembly is released and sUdes
into the water, and the forward section (nose) is rotated down until the cockpit is inverted and
completely immersed. After all motion stops, the trainee releases himself, pulls himself clear,
and surfaces.
Safety precautions are extensive. Normally, specially trained scuba-equipped swimmers are
located in close proximity. They observe the actions of the trainee and lend assistance if
necessary.
23-35
U.S. Naval Fli^t Surgeon's Abnual
Cwrrently being developed by the Naval Training^Equipment Center is a helicopter escape
training device which can be flooded, permitting practice escapes from a submerging helicopter.
Parachute Harness Release Training
Two devices are used to demonstrate problems associated with parachute harness release.
One detice, the Para-Drag, allows students to experience problems in releasing parachute harness
fittings under conditions simulating those i^*ich Would be found when an aviator is dragged
mtom surface of the water by his pai'dcfeute canopy. The otlier, an unofficial device, is
known as the para-drop trainer. With this device, the student cstti experience forces akin to
parachute-opening shock forces (around 7 to 8 G) and acquaint himself with the difficulties
involved in locating and operating the seat pan release mechanism during parachute descent.
HeUee^ter Hoist
In this exercise, each type of hoisting apparatus in current use (rescue hook, fluted seat, or
ding) is placed in the water where the trainee demonstrates hip ability to Board or enter each
device properly and is then hoisted vertically just clear of the water. Many squadrons use "live"
helicopter hoisting as a means of training. Arrangements are made with a helicopter squadron or
unit to perform actual hoists from an offshore location or from a nearby bay or lake. This
permits indoctrination in boarding both the rescue device and the rescue craft while in the
actual downwash created by the hehcopter rotor blades.
Ejection Seat Training
In addition to the above, pilots of ejection seat equipped aircraft receive training regarding
the ejection seat in their aircraft.
Procedure Trainer. Procedure trainers are available for many high-performance aircraft.
These are static devices which duplicate the specific seat installed in a particular aircraft and, in
some cases, a portion of the cockpit itself. Some operational flight b-ainers (OFTs) can be used
as ejection procedure trainers.
The procedure trainer provides indoctrination in the sequence of activities necessary for
successful escape - body positioning, actuation sequence, secondary methods of actuation, and
the like. In addition, ground emergency escape (nonejection seat) procedures can be practiced.
Static Seat. While afloat or when stationed at a place which does not have a procedure
trainer, a deactivated ejection seat may be used as a training device. Extreine Cfflfe Must be taken
to insure that the seat has been made safe. All cartridges, both propulsion and gas initiator, must
23-36
be removed and should be actually sighted by personnel prior to sitting or actuating seat
controls. This is best accomplished during required periodic inspection of the aircraft and seat,
when it will not interfere with aircraft utilization.
Ejection Trainer
Ejection seat trainers which provide aviators with dynamic ejection seat training are
available at aU Aviation Physiology Training Units (except those units involved solely with
multiengme trmaa%).
The Universal Ejection Seat Trainer Device 9E6 (Figure 23-22) utilizes a choice of ejeetiort
seats, a pneumatic charge, and a set of rails which project upward and backward at an angle of
18 degrees from the vertical. Prior to ejection, the height and weight of the aviator are taken,
the seat is adjusted for that height, and the pneumatic charge setting is adjusted for that specific
weight. This variable charge insures that the aviator is subjected to no more than 8 to 10 "G"
during the test. ii ' ;-■«,'>, • •
Figure 23-22. Universal Ejection Seat Trainer, Device 9E6.
The idrman performs the same pre-ejection and ejection tasks required, j^y an actual ejection
seat system. Upon actuation of the face curtain, the pneumatic charge propels the seat and
23-3T
OtSw NAvid FU^t Surgeon's Mamlid
weejipant up the guide>ra&^pi?oximately 10 to 14 feet. A ibieflt^ is provided for lowe^ to
occupied seat back down to ground level. This type of training has proved to be extremely
effective. Pilots who have made emergency ejections indicate that the dynamic training prepared
them for the the actual emergency condition and aided in relieving apprehension concerning
catapult firing.
For more information concerning aviation escape and survival traiiiii^ consult the U.S.
Navy Aerospace Fhysiolo^t's Manned (West, Every, & Parker, 1972).
Future Egct^e and Survival Systems
Ejection Seats
The performance characteristics and reliabiUty of existing seats are continually being
upgraded to match the increased performance of new aircraft. These improvements include
increasing the zero-zero escape capability to operate at high sink rates and high angles of bank at
low altitudes, more comfortable mid efficient ejrtremity restrfdnt systems, better seat
stabilization systems, more positive seat-man sepffi^f on units, and better training.
Future supersonic aircraft may of necessity move more and more to the escape capsule
concept. One advantage of a capsule is that it provides environmental protection during
ejection, descent, and after landing. The "fly-away" escape concept provides an aircrewman
with a secondary fh^t vehicle capable of gaining or maintaining altitude. This peranits him to
assist in his own rescue by navigatuif ovbe a limited rmige # ^hostile territory toward a
predetermined "safe" site. Pickup can then be made with a minimum of jeopardy to all SAR
craft and persons involved. Configurations for the systems include para-wing, |ixed-wing, and
rotary -wing designs (Walker, 1973).
Land md Sea Survival
Because of the success of peacetime search and rescue operations in effectively locating and
rescuing downed aircrewmen, survival kits are designed for short duration (24-hour) survival.
Survival during combat operations, however, may involve relatively long periods of esci^e and
evasion and require intensive first-aid knowledge and equipment. If captured, the self-ad-
ministered first-aid may prove to be the only medical attention the survivor will receive during
his time as a prisoner of war. Consequently, the medical supphes in the survival kit and training
in their use must be constantiy upgraded and reviewed to insure proper and effective
silf^EUhiiiiiistrttibn use liiider hi^-stress conditions.
Emergency Escape From Aitcn^
I ' Tfh^iiui^er^^ol -ftitaHties tseiaimn^ because of in-water parachute entanglement may be
decreased through the development of a promising system which combines parachute harness
release with Ufevest inflation upon entering the water. The chances of cold weather exposure are
being lessened by the improvement and redesign of anti-exposure suits. These suits now provide
better cold weather protection and are more acceptable and comfortable to the wearer. ' t /n
References
Dahnke, J.W., Palmer, J.F., & Ewing, C.L. ResultB of parachute-opening forces test program. Final Report,
National Piffaclmte Test Range, El Centro, California, April 1976.
1975 Emergmcy AirbtHfne Escjipe Summaiy . Naral Pax StKtbn, Nc«f(^, ViiitUtt (27 pagei).
ESCAPAC lE-IH advance stabilized ejection seat. Technical Report SffiC'Ji^SO, Douglas Aircraft C)o.» Img
Beach, California, 21 January 1974.
Every, M.G., & Parker, J.F., Jr. Biomedical aspects of aircraft escape and survival under combat conditions.
Prepared by BioTechnology, Inc/k^gr Cbnbaia N«k)14-72-C-0iar, Of^^^ of Nfeval Research, WasMllgton,
D.C., March 1976.
Every, M.G., & Parker, J.F., Jr. A review of problems encountered in the recovery of Navy aircrewmen under
combat conditions. Prepared by BioTechnology, Inc., under Contract N00014-72-C-0101, Office of Naval
Research, Washington, D.C., June 1973. ' ' . . . • »f-'
Every, M.G., & Parker, J.F., Jr. Aircraft escape and survival experience of Navy prisoners of war. Prepared by
BioTechnology, Inc., Undet Contract N00014-72*C-01ffl, (^c« -Sif N«ral Research, Washington, D.C.,
August 1974.
Every, M.G., & Parker, J. F., Jr. A summary of Navy air combat escape and survival. Prepared by BioTechnology,
inc., under Contract N000l4-72-t0i01, Office of Naval Research, Washington D.C., Februaiy 1977.
Ghuste^ 6.K 'fKfe ^tf^»st& of acceleration of short duration. In J.A; iffliea (Ed.), A textbook of aviation
physiology. London: Pergamon Press, 1965.
Goodrich, J.W. Escape from high performance aircraft. WADC Technical Note 56-7, Wright-Patterson Air Force
Base, Ohio, 1956.
Jones, Patrick, J. A brief history of ejection seat development. The Survival and FU^t E^uip^nent
Astodation'WinteT Jdumal, 1974, 7.
Kaplan, Burton H. Method of determining spinal alignment and level of probable fracture during static
evaluation of ejection seats. Aerospace Medicine, August 1974, 45(8), 942. ' <- /
Krefft, S. Cardiac injuries resulting from ejection. Aerospace Medicine, August 1974, 45(8), 948-953. ' • ' '
Latham, F. A study in body ballistics seat ejection. Proceedings of the Royal Society, 1957, Series B, 147,
127-139. .
Martin-Baker Afar* 10 Ejection Scat*, Martin-Baker Aircraft Co. Ltd., Middlesex, England.
Melzig, H.D., & Stteiidt, U. Escape measures for combat heUcopter crews. In W.L. Jones (Ed.), Escape problems
and manoeuvres in combat aircraft. AGARD Conference Proceedings No. 134, Soesterberg, Netherlands,
4 September 1973.
23-39
U.S. Naral fHight Suigeon's Manual
North American Rockwell, Co. Final Report NR71H-276, Columtnis Diviaoa, North American Rockwell,
24 September 1971.
Nuttall, J.B. Emergency escape from aircraft and spacecraft. In H.W. Randel (Ed.), Aerospme medicine
(2nd ed.). Baltwco-e; Willianis and Willdns Company, 1971.
Payne, P.R. Qm piuebittg back the frontierB of flail in^xy^ Presented at the AGARD Aero^ace Panel Speeiahat
Meeting, Toronto, Canada, 5-9 May 1975.
Pollard, F.B., & Klotz, G,D. Method for improving helicopter crew and passenger survivability. Presented at the
Ninth Annual SAFE Symposium, Las Vegas, Nevada, 27 September 1971.
Reader, D.C. Human factors aspects of in-flight escape from helicopters. In W.L, Jones (Ed.), £scape problems
and manoeuvres in comhat aircraft. AGARD Conference Proceedings No. 134, Soesterbert, Netherlands,
4 September 1973.
Rice, E.V., & Greear, J.F., III. Underwater escape from helicopters. Presented at the 11th Annual SAFE
Symposium, Phoenix, Arizona, 7 October 1S73. ^
Rice, E. v., & NInow, E. H. A review of hi^ perfomMince afceraft takeoff wd landing accidents. Freaerifed at the
Nmlh Annual SAFE %mposium, Las Vegw, Nevada, 27 September 1971.
Ring, S.W., Brinkley, J.W., & Noyes, F. R. USAF non-combat ejection experience 1968-1973. In Incidence,
distribution, significance and mechanisms of flail injury. AGARD Conference E^cee^gs No. 170,
Toronto, Canada, May 1975.
RotondO) G. Spinal injury after ejection in jet pilots: mechanism, diagnosifi, foUowup and prevention. Aviation,
Space, and Environmental Medicine, June 1975, 46(6), 842.
Stapp, J.P. Effects of mechanical force on hving tissue. L Abrupt deceleration and windblast Journal of
Aviation Medicine, 1955, 26, 268^88.
U.S. Naval Flight Surgeon't Himual. Prepared by BioTechnology, Inc., under Contract Nonr46l3(00). Chief of
Naval Operations and Bureau of Medicine and Surgery. Washington, D.C, 1968.
Walchner, 0. Pairachutists spin problem. Unpublished report presented at the AGARD Aeromedical Panel
Meeting, Copenhagen, Denmark, 1958,
Walker, H.R., Jr. Operational practicality of fly away ejection seats. In W.L. Jones (Ed.), Escape problems and
manoeuvret in combat aircraft. AGARD Conference Proceedings No. 134, Soesterberg, Netheriands,
4 S^^itemb^ 1973.
Weiss, U.S., Edelberg, R., Chariand, P.V., & Rosenbaum, J.I. Animal and huAum reactions to rapid tomUing.
Journal of Aviation Medicine, 1954, 25, 5-22.
West, V.R., Every, M.G., & Parker, J.F., Jr. U.S. Naval Aerospace Physiologist's Manual. NAVAIR 00-80T-99.
Prepared for the Bureau of Medicine and Surgery, DeparttUent of the Navy, Wai^bington, D.C,
September 1972.
Zeller, A.F. Psychological factors in escape. In proceedings of symposium on Escape from High Performance
Aircraft, Institute of Tranqic»tattott and Traffic Enpneeiing, Univerdty of California, Los Angeles, 1955.
23-40
I
o
c
CHAPTER 24
AmCRAJT ACCIDENT INVESTIGATIONS
Aircrirft Accident Investigation EeqiiiFeaSaits ^
Pire- Accident Planning
The Accident
Special Responsibilities
References
Appendix 24- A. Aircraft Accidents: Laboratory Instructions
Appendix 24-B. Outline Guides for Statements of Accident Survivors and Witnesses
Appendix 24-C. Sources of Detailed Information and Recommended Reading
Intaxluction
The need for meticulous aircrift accideftt investigations was demonstrated in the first fatM
ii^ll^ of a military flyer, Lieutenant Thom^fe'E. Self ridge, U.S. Army, while flying with Orville
Wri^t in Army demonstration trials at Fort Myer, Virginia, on 17 September 1908. In this
instance, Orville Wright was seriously injured, and Lieutenant Selfridge died from a head injury.
The investigation of his death led to the first use of protective headgear in aircraft, a program
which is undergoing cffntittuitig i:0ieareb and development to this day.
On 20 June 1913, Ensign WsiW BUlingsley beetoe:*he ®8t=»avy flyer to btf HM^ilti
aii K^tiofi ^deftfc Msia sdme ttHex^liiM p*diaemvti?i#'^e*aft toddinlf "nosed down,"
aMfi Ittigtt iiUin^ey lost all jjfinfifoi Th6 aircraft became inverted and Ensign Billingsley fell
out of the aircraft at 1600 feel. Lieutenant John H. Towers, who was in the aircraft with Ensign
Billingsley, survived by clinging to a strut as the plane spun to the water below. Although several
months were required for recovery from his injuries. Lieutenant Towers returned to flying to
continue a long and brilliant career as a naval ttyito«6i', serving as Chief of tiie ^iSSef '^of
Aerbnattti^ flfii^ 'Wrirtd *#'II, ito^ staf adttted (TuriibuU &
Lord, 1949). His '^lipirience with Ensign Billingsley was a major factor in the decision to install
pilot seat restraints in aircraft. Again, research continues to improve the design of aircrew
restraints, and aircraft accident investigations continue to provide important information for
these design improvements.
The analysis and comments of Wilbur Wright concerning the cause of the fatal crash of
1908, as stated in a letter dated 6 June 1909 (McFarland, 1953), serve as a basic model for the
afrcraft accident investi^A^on of today. The obvious effort to leave no stone unturned to
24-1
U.S. Naval Fli^t Surgeon's Manual
determine the cause and to recommend changes which would prevent the recurrence of a similar
accident is clearly reflected in this letter. These remain the key ohjectives in present aircraft
accident investigations.
It is estimated that at least half of all nav^ air<»aft accident investigations are conducted
with the participation of a relatively junior Flight Surgeon who is involved in his or her first or
second investigation. Because of this, it is common to encounter certain errors of omission. in
Medical Officer's Reports (MOR's) which are due simply to lack of experience with the rapid
sequence of events following an accident. This chapter is planned as a guide for the Flight
Surgeon, hopefully to help him avoid some of the common pitfalls encountered in these
frequently chaotic situations.
Aircraft Actddent bve8t%atl0ti Reqnireraentsr
Objectives
The primary area of concern for a Flight Surgeon in the investigation of a Navy aircraft
accident is the identification of human factors which might have played some part in causing
tijt aecident. The F%ht Sur^on, in addition, participates in the field investigation and
subsequent delibirations involving mechanical failures or other problems regardii^ material
aspects. He also reviews the stresses of the flight and the performance of the aviatOTS, to the
extent that these can be identified.
There often is an overemphasis in an accident investigation on finding a primary caused
While it is obvious that the primary cause should be determined when possible, and as early as
possible, an overemphasis here can resuh in neglecting other hnportant factors. An example of
this might be a bird strike where a jet engine ingests one or more large birds with a resulting
disintegration of the engine. In such an event, the primary cause is obvious. However, it remains
important that a thorough investigation be conducted. This investigation should deal with issues
such whether the pilot's performaniee piior to and followii^ the bird strike showed adequate
training for such an event, and whe&er airctaft protective and escape systems functioned
properly to prevent serious injurj^ to the pilot. The identification of other problems arising after
the principal mishap can be most useful in muiimizing injuries and possibly death in future
events of the same type.
Hie Investigating Team
The investigation of an aircraft accident is accomplished by a team, and it must always
be a team effort. The investigating team is the Aircraft Mishap Board. A Flight Sui^on
serves as one member, and he occupies a valuable and unique position due to the
24-2
Aircraft! Accident ]iiveiigt«tiG«i&
particular skills he can bring to bear in the investigation effort. The board itself is
required to be composed of at least four members, as follows:
1. The senior member shall be a naval aviator with wide aviation experience and other
qualifications warranting his appointment, and he ihuat be senior Itl 'ftlfe' iSf6$%M*^
performance may come iJM#ftel^e«tigiart^ ' ■ ' ' '
2. The second M^^r ftliPlfe ^ Aldiition Stfetjr OMce^ of ^ squadron who is the
Eepc^tiiig Ojiiidite^^
3. The third member shall be a Flight Surgeon.
4. The fourth member shall lift m (Mfft in maintenance of liie type aircraft
involved in the accident, ' ,
The Flight Surgeon is thft smly member of the investigating team who is not a line officer
and in many respects is the most independent member of the board. He is free, in his report, to
state his views as he sees them, with relatively little fear of retribution should anyone superior in
rank be embarrassed by his findings. This privilege, in itself, can be abused, and great caution
should be used in making statements in the written repctrt, which tend t» liecuse, impUcatfej^tjf
otfegywise hiam ^ ©j^rt^ ©f .a iB^tet of^^^^^ Such atatememte A^^idiGii^
absolutely neeessaiy to make a valid and pertinent point, and when the finding is demonstrated
beyond all doubt or, at least, represents a reasonable . inference based on available data.
Reports
The formats for the Aircraft Accident Report (AAR) and the Medical Officer's Report
(MOR) make the two appear to be complete and separate documents. However, these two
reports, in fact, must be complementary parts of a complete Aircraft Mishap Report (AMR).
Tliis does hot mean that the substance of the reports or the conclusions and recommendations
must always agree, but any human factors that appear to have contributed to the cause of the
accident should at least be addressed in the AAR, and any mechanical or operational factors
which affected the pilot's performance, caused an injury, or prevented his survival should be
addressed in the MOR. All members of the Aircraft Mishap Board (AMB) should participate^ to
some extent in the completion of bo^ tiie AAR and MOK.
Many of Ihe terms used relative to these investigations and reports can be confusing,
such as "Reporting Custodian," "ControUing Custodian," "Damage Code," "Injury Classi-
fication," "Aircraft Mishap," "Aircraft Accident," "Aircraft Incident," "Aircraft Ground
Accident," "Major Component," etc. The definitions of these terms and the criteria for
classification are included in Chapter 1 of OPNAVINST 3750.6 series. A basic woi^
knowledge of these terms is elementary" to an understanding of tte conduct of the
'investigations and the reports. -■"M.^ ■ •
24-3
Legal Issues
The purpose of the aircraft accident investigation is primarily and exclusively to produce
infonnation which wiU prevent future accidents of a similar or related nature. Occasionally, it
DM-f appear that tlie effprt mvas to be slanted toward finding fault or fixing blame. It should'be
clearly ianderst6od that this is not the puipose of .the invest^on in which the Flight Surgeon
participates. A separate investigation, called the JAG Manual feestigation or the Judge
Advocate General (legal) Investigation, is oriented toward negligence/liabUity aspects and other
potential legal claims (OPNAVINST 3750.6, Chapter IV). Persons involved in the aircraft
accident investigation and in preparing the AAR and the MOR are not at liberty to discuss with
thfe SAG ihyest^ators any infonnation they have uncovered. The JAG investigators do not have
access to any notes, statements, medical lab reports or other material that is gathered by fliese
board members for the AAR and MOR. The reason for db^oBSly is to present withholding
of information by witnesses. Any witness interviewed by the AMB must understand that he
cannot be held legaUy liable for what he states in his response to questions, and that all answers
wiU be kept confidential (OPNAVINST 3750.6 series, Chapter IV). However, as the examining
Ilh)^;^^ a Flight Surgeon may Be tte Wgole sbUfde^^of some medical information and may give
m^§m investig^feari-a fama mp&tt of iiquries, but he must avoid opinions, especially as to
^-Acddent Hanning
"There h much that can be done to make an ittyestigation go smoothly r^ardless of the
circumstances of a mishap. Even an experienced Flight Surgeon has much to do in pre-aceident
planning on reporting to a new duty station. The following outline may be used as a rough
checklist when reporting to a new duty station to help in preparing for unpredictable
emergencies. This is not necessarily in order of importance or even in chronological order. But,
an effort to complete this checUist soon'after reporting aboard can save much traie and effort,
if not real ^ef mi embarrassment, as as sendng t© faej^tate the transition to a new
assignment.
Get On The Team
The Flight Surgeon should make a determined effort to meet as many people as possible
with whom he will be working. This includes
1. Squadron/Station Commanding Officer and Executive Officer
2. Squadron/Station Operations Officers and Safety Officers
3. Parachute Risers (more properly called Personnel Equipment Speciahsts)
4. Search and Rescue (SAR) pilots and crews
24-4
5. Avis^on Medical Technicians (AVT's), some of whom may be experienced in m&l&mt
investigation
6. Local Flight Surgeons
7. The Senior Medical Officer. Althou^ a Flight Sui^eon may be assigned to an air group
or squadron, it is the Senior Medical Officer to whom he will be responsible on a day-to-day
basis.
Properly, his title is "The Medical Officer," and the other, more junior me^ed
officers, are "Assistant Medical Officers." The Medical Officer has been replaced in some
instances by an Officer-in-Charge (OIC), who may be a Medical Service Corps Officer or a
Nurse Corps Officer.
Learn the Equipment
The many dispensaries and sickbays within a single miUtary hospital contain a variety of
shoilar, but somewhat different, models of commonly used emergency equipment. ^p&imiM
or working knowledge of the equipment avaQable, h®e^©l^tewifWi^lW||h:*i®lia^^ Surgeon
must learn where this equipment is located in the emergency room, in the ambulance, and in
field medical kits. There also may be a separate field medical kit for the Flight Surgeon and for
the SAR Corpsman.
-. . ■ ■ .
Many dispensaries and air fields have asseiiitilett ^eld mvestigation kits, as shown in
Figure 24-1, ¥# m at ite. Often Ihis inchides a copy of OPNAVINST 3750.6, a
complete set of MOR forms, plastic bags, test tubes, syringes, an assortment of labels, marker
pencib, equipment for sample or parts collection, a clipboard with note pad, several pencils, and
possibly even dictating equipment. The location of this kit and its contents should be noted.
The location and inventory of first-aid and other survival equipment available within air group
or squadron aircraft also must be determined. The Safety Officer mi/m the pm-achute rig^s
can help with this information. ,
Study Local Grank ^ and Instructions .f i hin iL -- Ti
Each Naval Air SlatiOiii iqUifdrfdKj o* ship is Wssp^iiitfbK for its own local instructions
to cover various ph}||^s of normal and emergency operations. There are also crash bills for
the medical department and for individual squadrons. These will define duty stations,
responsibilities and authority under various emergencies, and what team members may be
assigned under the Flight Surgeon, to include, perhaps, various corpsmen, dental
techniGians, or dental officers, in the event of a major disaster.
MM
D,S. r4jv«i HightSBigeoa'a Msmd
FMdinY«p%8torkitforuBeatcraah8ite.
The aircraft crash bills of the different commands or departments should be reviewed first.
This is not the most interesting rea(fing ajid may be difficult for those unfamSuu- with the
terminology and format of the various instructions. However, the Flight Surgeon is responsible
for the content of every instruction that pertains to his activities. While it is not advised that
one read eaqh instructiori from cover to cover initially, a general scanning of the contents for
fpniliarizatioii with tie different areas of respDiiaibiHty and for learning where these
insyicfiora sire k^t wl^^
Hie AccUent
The first few hours following an aircraft accident are often chaotic md fi^strating at the
medical department. The foUowing is offered as a guide in the hope of preventing some of the
omissions and errors that have been committed in the past in the completion of MOR's. Errors
of omission in the first few hours may never be corrected, and the investigation can be severely
compromised. For this reason, proper organization and preparation are of the utmost
importance.
The principal guidelines are:
1 . Preserve life, minimize suffering, treat and repau: injuries.
244
2t @et blood samples early (see Appendix 24-A).
*tttdre may be survivora of a mishap who appear to have no injuries, and the reported
damage to the aircraft may seem so minimal that it may initially be doubtftil that an MOR will
be required. Therefore, it may seem pointless to draw specimens for carbon monoxide and
blood alcohol, to run a drug screen, or to obtain hemoglobin and hematocrit measures.
However, it must be remembered that a blood sample obtained later is of no value to '181^
investigation. If there is any reason to believe that an MOR will be required, blood samples
should be drawn early.
Appendix 24-A presents a su^sted poster for displays oa a Sispensa^ wsitifci* fiai^^ett
who may not be experienced in the tests or special handling required in aircraft accidient
investigations. Little harm is done if these specimens are not needed later, but much harm can
be done, both to the investigation and the individual aviator and his career, if they are necessary
and were not done. A negative drug screen is very important if the question of medication or
drug abuse is raised later in the investigation. Also, what may have actually been performance
degradation caused by c^lofel&bi^t^ttS^^^^Brteiffe^
error md a se^oii#l*Af(Mi^f¥felai^^ issues iMKy Sipf#iP'*El conflict with the
premise of not considering guilt in an accident investigation, such information may be quite;
important for the appraisal of an aviator by his superiop and peers. u
3, , Giv:e ^ squ^Qii Gomwidinf Wper (CO) and ExecutiYe Officer an early appraisal
,4
Review and memorize the injury classifications in OPNAVINST 3750.6, Chapter 1. The CO
must send a message within four hours following an accident which must include an appraisal of
injuries. This classification can be changed later if determined to be different.
4.1^ mt m^^Mx ^mimm
The CO and othet board members may be permitted a few questions while dressings are
being apphed or x-rays are being developed. This will be appreciated by them and will require
very httle time. If possible, let the survivor talk to his wife or family on the telephone as soon as
practical. No amount of assurance from a third party can put an ivfM^'s family at ease afe%ell
as hearing' las voice dn the'll^ephonfe attejr '^ey feairftlie ht^ been in m #feiitii&^fliatri^
small favor may not seem unportant at l||^jn^inefi^ but reftising to permit this, or .failW|| to
think of ,it, cffli.c^use unneeessiM:^^ . «
5. Get an initial informal statement on t«^e as soon as ]
Have the pileA i^H^wt&jrteii
outline, Appendix 24-B). This statement should be condde*0ii®W#i «^^ but
it should have times an4 otherT,|aLCtor^ that cam be of cpnsidepable importMce to, the
24-7
U.S. Nwrid, FHgJit Suigeon's Manual
investigation but which might be forgotten before the formal statemejUt ^mpleted. This
informal statement also reduces the likelihood that later there will be conflicting statements by-
various members of the flight crew due to slight memory warps and a self-protecting bias
developing during those few hours following a traumatic event. Survivors should be briefed that
thk fe a rough statement, and that they will have a copy available wiWn they complete tfieir
fprmal statement.
6. Contact the pathology laboratory for the time of postmortem examination of any
fatalities.
Attend and assist.
7. After immediate medical needs are met and statements obtained, join the othjer AMB
members in the field investigation.
Check in with the senior member of the board.
8. T^JkCi^^ AVT experienced in crash investigation tp the Crash site.
He will assist in making notes, gathering specimens, checking over roug^ MOR forms, and
pursuing any problems mentioned in the taped statement..
9. Contact the Naval Safety Center by telephone.
Do this as soon as practical after determination of tiie extent of injuries and aircrdft damage.
Request guidance on the extent of the MOR forms ^at will be required and any fecial
investigations needed. Call AUTO VON 690-7343 or commercial (804) 444-3520 during Eastern
Standard Time 0800-1600, and AUTOVON 690-3520 after hours. Ask for Head of Aeromedical
Division of Aviation Directorate.
10. Study crash site and aircraft parts to estimate magnitude and direction of cra^ forces
(See Chapter 25, Aircraft Accident Survivability).
lit Interfhw witni^^s and obtain taped or writteii statemepils ^ ispon as po£SibIe<
Attempt to have events described in chronc^ogiej^fXFdb^. A aesj^nee of evenia such as "smoke,
fire, explosion, change in engine noise" can be of vahie in determinitig the accident cause.
12. Make every effort to attend all AMB me^iffis^.
It might be necessary to miss one if assisting in the post mortem, but only duties such as 'this
i^ould prevent attendance.
13. Coffiplette the rou^ MOR as sdon as po^iaible, and concentrate on unanswered questions
m later interviews and board meetit^.
Keep ydiir magor goal in mind — determining Ae causes of preiventable injury and death.
24^8
Mrcraft Accident Inv^ti^iioBS
14. Complete the smoolli MOilb, analyaa and eojaaaients. '
Special ResponBibilities
la atdBtian. to the requiremeute for pj(«-ftac|^ft RlllPWg^ em^igency response, and active
partidpation. as a member of the Aircraft Mishap Board, tiere are other responsibihti^ ^t
should be kept in mind.
One is for objectivity. It will often be found fliat within the first few hours following an
accident, information >vill be uncovered which will give a good indication of th@ipl^hlblPM^
or even an "obvious" cause of the accident. Has "best guess" is important to the Naval Safety
Center and to other commands flying the same type of aircraft, especially if there seems to be a
mechanical problem that may be causing a hazard to others flying the same type of aircraft.
Therefore, this information will be relayed immediately by message. Occasionally, this results in
a decision to ground all similar Navy aircraft until the problem can be resolved. From an
investigator's standpoint, one must resist the Miliftktoit td ©riewt and concentrate
gathering evidence to support initial Impressions, th^by overlooking other important
problems. Th% &St two or three days' 6f an iftvesftigation should be devoted to gathering all
possible information concerning the accident as if no specific cause were suspected. Use of a
complete set of MOR forms (Sections A through 1) will help in the attempt to consider aU
possible causes and contributing factors. It also may prevent loss of valuable information which,
if sought later, may be difficult or impossible to obtain because of factors such as movement of
the wreckage or the d^arture of a witiieM.
In any crash resulting in injuries or death, and especially if a survivor is admitted to a
hospital, one must collect all flight and personal survival gear (boots, suit, helmet, gloves, etc.)
in a plastic bag and maintain close possession since such gear is easily misplaced or pilfered.
Correlating injuries vrith damage to personal gear is an essential part of the investigation and cmt
lead to design improvements in the gear.
Another responsibility that must not be neglected is that of confidentiality. Rumors and
conjecture have a fleld day through a base or ship foUowing an accident. Many people would
Uke to know aU of the details. Some wiU be heard creating or repeating rumors that the Fhght
Surgeon knows to be false. He must resist any urge to stop such rumors by spreading the truth.
Tactful evaaon is the best tactic. A simple "We are not sure yet" should suffice for most
inquiries, while "I've seen no evidence of that" may dampen a false rumor potentially damaging
to someone's reputation.
24-9
U.S. Naval Eligjit Surgeon's Manual
The manner in which the Flight Surgeon meets the duti#v«id ^sponsibiUties of an accident
investigation will greatly affect his appraisal by his peers and seniors in the Navy as an officer, a
Flight Surgeon, and a physician, perhaps to a larger extent than anything else he may do
while on active duty. Efforts in this regard should be performed with the same respect for
objeiStive, aesairate appraisal and confidentiaMty thai is expected of the Flight Surgeon in his
role as a personal physician. Best efforts will be grfeklly appi^ciated. If a Flight Surgeon does
nothing more than prevent one major accident in a 20-year Navy career, he will have saved more
than his entire pay. While a Fhght Surgeon will never have absolute proof that he prevented an
accident, he must continue to do his best to prevent damage, injuries, and deaths without the
credit or even the certain knowledge that he has done it.
References
Department of the Navy, Office of the Chief of Naval Operations. Navy aiueraft accident, incident, and ground
accident reporting proeedui^ (OPNAWST 3750.6 series).
McFariand, M.W. Papen of Wabur and OrviOe Wr^ht (Vol. H, 1906-1948). New York: McGraw^Hffl Book
Company, 1953.
TumbuH, A,D., & Lord, C.L. History of United States naval aviation. New Haven: Yale Universi^ Press, 1949,
Airctaft Accident lip^estigatioiis
APPENDIX 24-A
AIRCRAFT ACCIDENTS: LABORATORY INSTRUCTIONS
Attention: Laboratory Wateh Standerg
Routine procedures required on pilots and aircrew following an aircraft accident, with
specimens to be obtained as soon as possible.
1. Blood Alcohol ~ Prep arm with soap and water (not alcohol swab). Draw one large,
red-stopper tube and allow to clot. Spin specimen down, draw off 4cc of serum and place in
red-stopper tube labeled: serum for blood alcohol, patient's name, rank, service number, unit
attached, and the date and time specimen obtained. Place specimen with blood alcohol form in
freezer in laboratory.
2. Carbon Monoxide — Draw one lavender-top tube and fill tube as fuU as possible being
careful not to let air into the tube. Attach label with: carbon monoxide specimen, patient's
name, rank, service number, unit attached, and the date and time specimen collected. Place
speeWen in f esfii|erattfr door |pe^ " " " '
3. Hemoglobin and Hematocrit — Draw one full, lavender-top tube and peilomi tetti in our
laboratory. Label tube in detail as above attidsave in f efngeratof door in green box.
4. Aliquot — Draw two large, red-top tubes, allow to clot, ^in down, draw off 8cc of serum
and place in red-top tube. Label in detail as with other specimens and |(]^ce in freezer for
possible future studies. Retain for 90 days.
5. Blood Sugar — Draw one gray -top tube, label and place in green box in refrigerator door.
6. Urine Sample — Obtain at least 75cc of urine if possible, and perform routine urinalysis
in our laboratory. Label specimen in detail and save remainder in refrigerator for drug st^reen if
ordered by Flight Surgeon.
7. Extra Tubes — Draw two large, red-top tubes and place in green box in refrigeratcHr in
laboratory with detailed labels for additional tests that may be ordered by the Fli^t Sijigeon.
Note: Recheck all specimens to insure that all required informa*
tion including date and time obtained is on all labels.
8. The technician should leave his name and phone number in a designated place.
Total Specimens Saved in S^irigerslor or Freezer
Large Red Top (4) (1 with serum only in freezer)
Lavender Top (2) Two
Gray Top (1) One
Urine Specimen 50 ml+
24-11
U.S. Naval Fligtit Sutgeon^'Manual
APPENDIX 24 B
OUTLINE GUIDES FOR STATEMENTS
OF ACCIDENT SURVIVORS AND WITIVESSES
Instructions to Survivor
Please dictate a statement in narrative form of the sequence of events, your actions and
reactions up to . the time of the accid^t. lachide all exact times or time intervsts said other
numeric^ data (airspeed, altitude, etc.) that you can recall, and give your best estiinate or
opinion for those that you cannot recall specifically. You will be given a copy of the transcript
of this statement to make any corrections or additions of facts that you may later recall to
include in your formal statement.
Take your time and try to keep the statement in chronological order, but if you recall
something significant after you have gone past a particular phase, go ahead and dictate it,
prefaced by the words "special note," then proceed wilb, the regular sequence. It is important to
include all details of delays, frustrations, malfunctions, or other prpblettis which mi^t have
interrupted your normal procedures or habit patterns in each phase.
While dictating, try to review mentally each phase of the flight before dictating that
sequence of events.
Read Entire Outline First, Then Begin Dictating at Phase #1
And Remember to Dictate Time or Time Intervals in Each Phase
1. Flight brief
2. Weather brief
3. Flight plan filing
4. Preflight of aircraft
5. Ehg^ie stsuftup
6. Taxi/turnup, engine and control checks
7. Clearance
8. Takeoff
9. Climb-out
10. Progress of flight
11. First signs of trouble detected and response
12. Accident phase — loss of -p&wer, loss of contiol, etc. Include all details and thoughts at
the time as to cause and present opinion, if different.
13. Escape phase — egress from aircraft: ejection, bailout, or ground egress. Include all
details of normal functions and difficulties, opinions of cause, md difficulties or injuries.
14. Survival/rescue phase. Include all details from time of egress to arrival at medical
facility.
24-12
Instm^CH^ to Wititesi
Please read the following instructions before beginning dictation, then foUow as closely as
possible as you dictate. iiiclud@ all detaijU tiiat yqu can tecall that you observed or heard. Try to
keep the statements in chroii^^gical order^ fc^jf feel free to fi^d any ^^|i^fiint^inf!Q]|OTation you
may recall even if out of sequence. Please comment, however, on the proper sequence for such
an event. Include your best estimate of all times and/or time intervals between distinct events.
Think over your statement before beginning, then dictate in your normal conversational tone.
Flease make special effort to describe exact details of observations of such important signs as
1. smoke/fire; its source or location
2. inflight signs of aircraft damage
3. unusuid or abnorm|d.lH|^M^eha!mi|:$erktic»
4. normal or abnormal engine noises
5. aU detaitirof any'obe^ii|le^@^oii<A '
6. at^tude of aircraft on descettt. ' '
II It
24-13
AFPENDIX,24-C
SOURCES OF DETAILED INFORMATION AND RECOMMENDED READING
Tkem arie a idimber of excellent gourc^^ ' of M^fonhMdii whi^ wil 'fie hMpW in
paiticipatioh itt the Aircraft Mishap Board deliberations and in prepi^ng k proper Medical
Officer's Report. It is not the purpose of this chapter to repeat or summarize these references.
Key sources listed below are titled, and a brief explanation of their contents is included. They
can save much time and effort if utilized. *
OPNAVINST 3750.6 Series - The Navy Aircraft Accident, Incident,
and Ground Accident Reporting PrM^dfitres
This is the single, most important source of guidance and is indispensable in preparing an
AAR and MGR. Regardless of the number of accident investigations one participates in, it will
be found ^t this instruction must be referred to repeated^;. It is recommended that a copy of
this instruction be carried constantly during ihe investigation and bowd meetings. While the
complexities of aircraft accident investigations and analyses can seem, endless, most of the
questions that need to be answered by the Flight Surgeon in completing his report are included
in ibis instruction. Be certain that you have a copy of the latest revision. This instruction, like
all otiiers, is periodically updated.
NAVAER 00-80T-67 - Handbook for Aircraft Accident Investigations
This handiiook gives detailed guidiuice in evaluating overstressed metal and in determining
whether this occurred prior to impact, during a &e, after a fire, or before a fire. The handbook
also discusses ways of delmnining aircraft angle of impact; procedures for interviewii^
witnesses; properties of aircraft structural materials, various fuels, and other aircraft fluids; and
provides guidance on illustrating findings with photographs and diagrams. Never underestimate
the value of a good diagram in these reports.
NAMI PED-I9 - The Manual of Aviation Pathology
This publication, originally printed in 1962, was reprinted in September 1973 and is an
invaluable aid to the Flight Surgeon in his effort to determine effects on the body from impact,
bums, and toxic substances. It also tells how to gather and preserve Epecimens and to order
proper tests* However, some of &e infotmntion in book may now be obsolete oi* hoidled
differently in your area. The essential points should be clarified by your locd pathologist or
central laboratory.
24-14
AJroraft Accident InvestigatioiiB
OPNAVBVST 3710.7 Series - NATOPS General Flight and Operating
Instructions
This manual is most helpful when there is the possibility of a flight rules violation or some
error in general aviation safety. It has chapters dealing with aircraft lighting, air traffic control,
required survival equipment, general safety rules, emergency signals, and requirements for
proficiency and qualification. The manual also covers flying policies for Flight Surgeons. The
chapter on survival is e^eciaUy recommended, as this jncludes infomation on physical fitness,
emotional upsets, immunizidions, and self -medication by fl%ht p^sonnel.
While medical ffii^ce occasionally may be taken lightly, the rules within the NATOPS
Manual are not since any NATOPS violation is a very serious matter for a naval aviator. This,
in effect, then becomes the military avenue for enforcing medical requirements.
The Manual of the Medical Department
Chapter 15 in this manual presents the physical requirements for aviation personnel, with a
definition of aviation class and service group. Reference to this manual may be needed to insure
that Ibe aviation personnd, involved were physically qualified by all current standards at the'
time of the flight and are qualified prior to returning to flight status followmg the accident.
The U.S. Naval Fli^t Surgeon's Manud
This manual includes chapters such as Aerospace Toxicology, Acceleration and Vihration^
and Emergency Escape from Aircraft, which will be useful in various phases of aircraft accident
investigations.
24-15
r
"1
O
n
J
o
CHAPTER 25
AIRCRAFT ACCroENT SURVIVABILITY
Introduction ,
Crash Survivability
Human Tolerance Limits
Survivability Calculations
Reference
Appendix 25-A Basic Trigonometric Functions
Appendix 25-B Deceleration Pulses and Equations
Appendix 25-C Sample Calculations of Landing and Crash Forces
Introduction
The interaction between crash investigator and im^ engineer traditionally is an
after-the-fact matter. The infoimation?lii»]iecte# at that tnDi^^ h0wii!i^,t^.-be^«i^^
Findings presented in the Medical Officer's Report (MOR) of an aircraft accident investigation
can lead to the identification of correctable design deficiencies. This is especially true when it
can be shown that the crash forces in a fatal aircraft accident should have been survivable. The
question then becomes "Why did the deatii occur?" A Flight Surgeon, serving as a crash
investigator art#=1iiWg^fi«||ei!P invegtig^ (^t|«i^«ill«-#{#design engineer* with a
reais^n|l»le aM»'esiiiB6iiy)S 4e^i|iK>@igw@ adth^sse4, md«hort-teriHiidlM^to
canbe madeidnfaoipMWejcaf^sumvability. ''• v,, , ; ; t^Jte ijnniit
Crash Survivability '
This chapter presents survivability principles and describes proce^(||^^^oic.Palj^latill^^alih
forces. While the calculations more frequenlUry f^i#iiSp|^,witiioMt ^
restricted to such aircraft. , i „„:t.«.i - ^ . • ^
Every MOR should directiy address crash survivability. The investigation of injuries and
d^atiia from crashes wMeh can be shown to be survivable will identify problems such as weak
seat-to-floor tiedowns, non-crashworthy fuel systems, helmets that offer marginal head injury
protection or that may themselves cause lethal injuries, and rudder pedals that fracture tibia and
prevent escape. For tbo long it has been assumed that injuries or fatalities naturally occur in
accident sequences. It is neither luck nor fate when an aviator survives.
25-1
U.Si^^l4iiii:i4'^|^t Siugeon'B Manual
Hie CompponentB of Survivability
Survivability requires two things — the presence of tolerable deceleration forces and the
continued existence of a volume of space consistent with Ufe. This section highlights the
mathematics of crash force calculations and considers the elemental components of sur-
vivabdity. ,
Calculating the crash forces in an accident is an inip«ffect art. Using known speeds, stopping
distances, and gravity constants, it is relatively simple to calculate the deceleration forces
imposed on an airframe. These numbers must then be viewed from the perspective of the
aircrewman for whom other factors serve to increase or decrease the acceleration (G) forces he
must tolerate to survive. A reference tool is the acronym "CREEP." The CREEP factors are
C = container
R = restraints
E = environment
E = energy absorption
P = postcrash factors.
Ifte C^niakier, An airframe thai dia^tegrates or allows penetration by objects, or one that
fails to otherwise preserve an appropriate volume of hving space can be unsurvivable. The use of
brittle alloys in larger airframes that trade off pressurization integrity for impact resistance has
been a source of container problems. Another obvious example is the invasion of the aircrew
living space by hehcoptep tEanatnismcaM JB«^ blades strike the ground. The limited
space between crew seats and controla,^ l^te^oird^; or dntdde objects with which the crew can
collide is also a container problem. The thoughtful investigator will evaluate the living space
remaining after impact forces have been dissipated, remembering that some ductile metals can
rebound after they have compromised volume, leaving few traces of their brief invasion into the
aircrew compartment.
The Restndnt Symik. To mcv^ W 0^^s^^J3^ with a system of straps deseed to
withstand a 10,000 IB. load is fUtile liftliiiittiesyi^ill is mahitained and used properly. Worn or
damaged straps fail with reduced loading. Unused restraints speak for themselves. Loosely
secured restraints present a special problem because of dynamic overshoot. This occurs when
the aircraft has begun deceleration over time before the crewman actually impinges on his
straps, which may either fail or. rebound. Crash force calculations under the kttef drcumstoces
#fll fee til ^kafhf 41 teiato' a^i^ekMUfh,
Ten thousand pound test straps affixed to a seat which in turn will separate from the floor
with a 4 G deceleration in the x-axis or 1.5 G deceleration in the y- and z-axes are a complete
25-2
mismatch. Loose restraints invite submarining in which the aircrewman can exit the seat in
whole or in part without unfastening the restraint buckle. Buckles that open under survivable
deceleration forces or that cannot be opened with one hand must be identified. Those buckles
that cannot be opened if suspended inverted or that are so complex as to defy quick openiiigljlj
non-mcrnmoM fuiist dso be elitninated from the inventory. In^a teek iiid^td^ed mtty
lock autoin^!^ill^wadict9iM« Iwt if #ie:ti8ite»atii*|i W'ilei£^%Q£ia$lW^^a oi^iilt@f
some ainmipt-otf teasel #ii#«qi^tates with dynamic overshoot.
The aft-facing seat, which ostensibly requires a. simpler restraint system, must withstand
higher G-loading than its forward-facing counterpart because its center of gravity is higher. A
seat designed as forward-fadng which is installed facing aft wiU predietably £ui'ilBigtf
G-loads. The dde-facing seat exposes its occupant to the least survivable G-loads, restraltdng
systems not^tiMMltdiE^*:: ' .i:ri ,
ITte Environment. There are many features of the cockpit enviroiunent which affect the
ability of an aviator to withstand crash forces. Pyrolyzation products from fires involving
eleetrtc$id iiMilation and polyutethane' iocoiii^'tHenuating or decofative panels can prodttee?
in-IQ^t incapacitation whidi reduce iui^iil el^c^^^ The vsi^d is tixt^^^^^fi^^^^^^^^
hydrocarbons present in a cockpit fire at low ambient pressures, with or without the presence of
open flame. The toxicological properties of substances in a sea-level environment may be
substantially altered when the event occurs at altitude.
Atto^iep "efivtetitttental factor wMch influenees crash sunlvabiUty is the speed
emei^ney ^ess can be accomplished. If an aircrewman or a non-airerewman has been irtdff&l}
in specific emtageiicy exit procedures, and he is then confronted with unanticipated
impediments to a fast exit, survival chances decrease. The , capability of a crewman to egress
rapidly must be considered in assessing survivability.
Energy Absorption. TlW aibrfe abs^o^^Sm ^&at occuti in Hie atimttie^'befdre the
airer<^#miiit% basiy becfe^mM €ie i^ieif^B^, steler Is^rate'fcrewman. Honeycomb construction,
stroking seats, and expendable space and metal are a few of the techniques available to the
engineer for increasing survivability. Landing gears that can absorb a sink rate of 35 feet per
second are expensive, but they are a reality and will increase the chances for survival.
It is ©nly ne€©KSu*y that ertergy absorption device be built to fSBSt^b a'{it^iQtf '^t£^|p§t
forees. If mch devices can abs&rb 20 G of vertieii impact in a 40 G crash, man can normally
hatltUle^et«4naining20. '
25-3
U.S. Siaxfi. Iligbt Siirg^n,lB Martial
Postcrash Factors. Statistically, the single most important postcrash factor affecting
survivability is fire. It is a safe assumption that if fire is not yet present at an accident scene, it
will be shortly. The atomization of fuels that occurs simultaneously with destructive impact
rd^^ates all aviation fuels to an equally dangerous potential, regardless of flash points, vapor
pressuies, or oilier ]|iboratory>-measiired proferti^B. The U.S. Anny hm led the way in the
evolution of crashwiirthy fud systems designtd to prevtent or atomization. These
l»eakaway, fail-safe valves, pipe connections, and tanks, which aU prevent escape of fuel,
dramatically changed the previously grim statistics of helicopter postcrash fires. The continued
acceptance of belly fuel tanks located beneath or directly adjacent to crew and passenger
compartments, where impact and abrasive forces must compromise these spaces, no longer
merits tolerance.
Use of thermal protective garments and readiness of firefighting equipment both in the
aircraft and at the duty runway edge are standard procedures in the military. These measures are
substantially less effective, however, than the designing of an airframe to absorb impact without
fuel spillage and subsequent ignition. A survivable crash, witii mild to moderate G-forces that
produce associated limb fractures in passengers md crew, rigidly becomes a trage^ when
postcrash fire occurs, and timely egress becomes impossible.
There are a myriad of postcrash factors influencing survivability. Fire is the most important.
Others, such as poor communications, inadequate rescue capabilities, water survival require-
ments, and training problems should be evident to the investigator as problems tihat may require
corrective action on a local level. The problem of postcrash fire, however, remains nearly
universal.
Human Tolerance Limits
In eat^ of the three major axes of acceleration/deceleration, there are "best guess" estimates
of human tolerance (Crash Survival Investigators' School, 1976). These numbers are imperfect
because of the indirect methods available for their establishment. As pointed out above,
calculations of G-forces imposed on the airframe may bear only Uraited similarity to the forces
imposed on crew and passengers. The human tolerance limits shown in Tables 25-1 and 25-2,
along frith the CREEP factors, offer an investigator a rule of thumb around which survivability
estimates can be made. In using these numbers, it is important to appreciate that as the time of
expQfpi^ to hi^-impact forces int^ases, fbe tolerfmce level decmdsfs.
For deceleration, duration of the forces and the rate of onset can significantly alter human
,respon8e. The body acts like porcelain in short-duration exposures with a high rate of onset, but
£1^ a hydrauEc'liystem in longer exposures with a d0wa- rate of onset.
I
1 ^
25-4
Aiitstafy. Aecident SarvivalHlhy
Position
Limit
Duration
Ey«balls-out (-G^J**
45 G
0.1 sec
25 G
0.2 sec
Eyeballs-in (+G^)
83 g'
a.
0.04 seic'
Eveballs^dWri t*Qji
20 G
0.1 sec
Eyeballs-up (-G^)
15G
0.1 sec
EyeNlls-left (±Gy) .
9G
0.1 sec
-right
*FuUy r«it(3||i|^«^btt^a^|){^^^^4^ impair 9tu^ to .2li9j^/seG${is§Jj
•'For lap belt fwtrSim wly.-Gx tolerance may be cat to 1/3.
(from Crash Survival Investigators' School, 197S).
Regional Impact Forces Known
to Cause Bone Fracture or Concussion
Body Area
Force
Duration
Head (frontal bone.
180 G
0.002 sec
2" diam. appiication)
57 G
.02 sec
Nose
30 G
•
Maxilla
50G
•* •
Teeth
100 G
*
Mandible
40 G
Brain (concussion)
60 G
.02 sec
100 G
.005 sec
.1806
'Duration figures not available.
(fr^m Crash Survival Investigator's School, 1976).
Where the crash forces are not clearly in the x-, y-, or z-axis, it may be appropriate for an
investigator to solve for the vector most nearly approaching the actual crash force vector and
extrapolate to the likely survivability limits and exposures. Table 25-1 does not present a
maximum, or even an average, for survivable crash forces. It does show that level of force which
25-5
U.3i Nilval Flil^tSutgeQii'B Manual
is known to be eafe, and beyond which body damage could reasonably be expected to occur.
These limits presuppose proper utilization of a four- or five-point restraint iy>rstem by a healthy
subject.
The limits shown in Tables 25'1 Euid25-2 are not so fixed that to exceed them is
antomatieally equated wfth non-«urvivabittly> It is also not valid to extrapolate from these limits
directly to the G-forces calculated for a pven mwh situation. When, a decision on the
survivability of a given situation must be made, the following considerations may be helpful. If
the calculated crash forces on the airframe exceed the human tolerance limits by a factor of two
or more, survivability is unlikely. If the limits are exceeded by a factor of 0.5, survivability is
doubtftil. If the limits are exceeded by a factor of 0.25 or less, survivability can be dependent
on the CREEP factors. If fte fimits are not exceeded, airvivabiHly is expected, ^though
individual variations in G-tolerance and the CREEP factors still remain extremely important in
determining survivability.
&irvivability Calculatioiw '
The investigating FU^t Surgeon or physiologist is not expected to be an engineer, a
maintenance officer, or qualified in the type of aircraft involved in a mishap. Rather, he must
use the talents of the other Accident Investigation Board members and the consultative
expertise available to them, to get the data needed for his calculations. Members of the accident
investigation team can supply the following information:
1. Initial and final velocities for each impact
2. Vertical stopping distances, measured in feet, including depth of gouges in the earth,
depth of water entry before stop, depth of damage to the underside of the aircraft or extent of
compression of energy-attenuation devices, such as oleo struts and stroking seats
3. Horizontal stopping distances, measured in feet, including length of gouges in the earth,
length of airframe compresdon in the horizontal plane, backward displatement of each wing,
empennage surfaces, and engine/fuselap, or actual stopping distance after water entry
4. The shape of the deceleration pulse which most nearly reflects fbe buildup and
dissipation of stopping forces.
In cases where the Accident Investigation Board cannot establish values, the members must
estimate a range for the values and make maximum and minimum estimates. Where the range
erd^^ l3ie expected limits of survivability, it may have to be hainnwed. For example, if the
Board concludes £fiat iKe fnier^ft wais traveUiig between flip and 100 imoi^ just prior to impact,
and if can .lie shown t]iat 9^ knots is idie outfAde Mmit of fliat sordviOjility envdiope, it may be
25-6
AinxKft AceidQilt SmcvividMlity
neeessary to re-evahiate the evidence so iliat a more precise liuqpeed estimate can be
obtfdned.
Velocity measurements are extremely important because they are squared in the
numerators of the survivability equations (Appendix 25-B) and can considerably magnify any
errors. Stopping distances liM^ toxy be letaMvely short, appearing in equaticiin deiusitiinatom,
El^lf^ need precistoti md, where poadble, should be measni^d rtdlier than estimated. For
convenience, an electronic calculator or slide rule is recommended to perform the actual
mathematics involved, remembering that precision beyond the first decimal place is unrealistic.
IVigonometry
Use of basic trigonometric functions (Appendix 25 -A) is necessary in establishing force
vectors. A brief review of terminology and useful principles of trigonometry foUows:
The Hypotenuse — the side of a right triangle opposite the right angle
The Opposite Side - the side oppoate a spedftc an^ of a triangle
The Adjacent Side - the side touching a specific angle of the triangle.
In a rigbt triangle, the hypotenuse is not 8o identified.
Sine of an An^e — a fraction using the opposite side dimeiuSon as
the numa^tor and the hypotenuse dimension as the denominator
Cosine of an Angle — a fraction using the adjacent side dimension as
the numerator and the hypotenuse dimension as the denominator
Tangent of an Angle — a fraction using the opposite side dimension
as the numerator and the adjacent side dimension as the denominator
Pythagorean Theorem — In a ri^t triangle, the square of the
hypotenuse is equal to the sum of the squares of the other two sides
(a2+b2 = c2).
Sum of Angles — The sum of the angles of any triangle equals 180**.
The basic use of the trigonometric relationships in establishing the parameters describing an
aircraft crash is illustrated in Figure 25-1. If the dimensions of any two sides of the triangle or
of one fflde and the impact aii^ can be obtainedlty actual measureni^nti lbQ 0>|tee9> parameters
can be calculated. j -f
35-7
U.S. Nwal Fli^t SurgeontoMttid
a = Opposite Side
(Sink Rate)
sm a
Opposite
Hypotenuse
b = Adjacent Side
(Ground Speed)
■ Impact
Angle
cos a =
Adjacent
Hypotenuse
tan a =
Opposite _ a
Adjacent b
The Pythagorean Theorem: + =
Figate 25-1 . IHgonottiettiss fd^oaahips used: to. cdcuUitang msh force*.
Deceleration Pulses
The Aircraft Accident Investigation Board should identify the most likely deceleration pulse
shape. The decay or increase of the deceleration forces during the time of application must be
represented diagramaticaUy. The various khpids of pulses and the corresponding deceleration
equations are illustrated in Appendix 25-B. There are two groups of formulae; tiie first is used
when the final velocity, (Vf), is zero and the second when Vf is not zero. Each case must be
treated separately. The following are examples:
Rectangular Pulse — reqnires unchanging G-forces over the period
beginning with the initial velocity and ending with final velocity. An
example is the deceleration of a normal landing using constant
braking force.
Triangular Pulses — recpiire constantiy changing deceleration levels,
either increasing, decreeing, or a combination of both. An example
of a constantly increasing force is a crash that digs a deep hole. An
example of a constantiy debreasing force is impact against an object
25-8
«^reraft Accident SQZviy«i|iility
that gradually gives way like a tree top. A combination of increasing ,» - ^ . .
and decreasing forces would be expected as an aircraft flew through
trees or brush. Water entry also frequently has increasing then
decreasing forces.
Half -Sine Pulse — requires constantly changing rate of deceleration as
in an arrested carrier landing.
Interpolation of Pulses. If the deceleration pulse of an impact does not match a pulse given
in Appendix 25 -B, the forces of the two pulses that most closely represent the situation must be
calculated. The actual forces are interpolated between those answers as shown in Figjure 25-2.
The Board determines the deceleration pulse to be: ■ ■ *
G
time
time
The actuai answer will lie between the two.
Figure 25-2. bterpdatidia of Seceloration pulses
(from Crash Sumval Investigatois' Schod, 1976).
25-9
, U.S:NinridMi^tSiii;geon'BMaiititd
Guide for Piroblem SiMEigi ilte^
The most common errors in calculating ctaSi forces are not mathemaii'C^ mistakes; they are
errors resulting from inattention and inaccuracy. The following steps are offered to make
successful calculations more likely:
1. Express all velocities ii^ feet per second (fps) and all distances in feet. The conversion
factors are
. '. mph X 1.46 = fps
. " kts X 1.69 =
%. Draw a large diagram and labd every known distance, velodty, and an^e.
3. Designate the deceleration pulse or pube possibilities and the final velodty.
4. Calculate vertical and horizontal velocities.
5. Calculate vertical and horizontal G-forces using the appropriate formulae
(Appendix 25-B).
6. Calculate the resultant G-vector from vertical and horizontal G.
7. Calculate the time of the deceleration pulse from the appropriate formula
(Appendix 25-B).
8. Estimate survivabihty potential using Tables 25-1 and 25-2.
Hie Inadequacies of the Survivability Calculations
Numbers are magical. They confer scientific precision where it may not be wholly
appropriate, and this is the case for survivability estimates. The formulae make no provision far
dyttionic ovenhoot, for exam|^, or for rebound of cockpit components which mi^t be
harmful to the crew. The squaring of eilimated numbers in the equations compounds an error
by its square. And finally, the human tolerance levels in Tables 25-1 and 25-2 were derived in
laboratories, in retrospect, with imperfect and sometimes unrealistic techniques. None of these
limitations, however, destroys the usefulness of the calculations. They provide the best available
mediod for approximating the forces acting upon aircraft and crew in crash situations.
l^aiiS^fei d landing and crash calcuktions which may be helpful as models are given in
Appendix 25-C.
Reference
Cheh Sutvival LivestigatoiB' School. Arizona State Univenity, Tempe, Aiizona, 1976.
25-10
Sina.
Opposite
Hypoteiiuta
Sine
Cosine
Cosine
Adjacent
Hypotenuse
Tangent
0.000
1.000
0.000
.018
1.000
.018
.035
0.999
.035
xm
.999
.052
.998
.070
mi
■ifsn>
.088
.105
.995
.105
.122
.993
.123
.139
.990
.141
.156
.988
.168
.174
.985
.176
.191
.982
.194
Mn
.213
22S
.242
mo
.249
.259
.966
.268
.276
.961
.287
.292
.956
.306
.309
.951
.325
.326
.946
.344
.342
.940
.364
.358
.934
.384
.375
.927
.404
.391
.921
.425
.407
.914
.445
.423
.906
.466
.438
.899
.488
.454
.891
.510
.470
.883
.532
.485
.875
.554
.SOO
577
.515
Mm
.601
.630
.848
.625
.545
.839
.649
.559
.829
.675
.574
,819
.700
.588
.809
.727
.602
.799
.754
.616
.788
.781
.629
.777
.810
.643
.766
.839
.^6
.755
.869
.669
.743
.900
.682
.731
.933
.695
.719
.966
.707
.707
1.000
Tangent
Opposite
Adjacent
Angle
Sine
Cosine
Tangent
45°
707
.707
1.000
Aft
. / 1 ?
.695
1 .036
47°
1 / O I
1 .072
Aa°
4o
./*to
.009
1 .1 1 1
As
■QOD
1 iF>rt
1 . 1 w
o
DU
1 107
1 . 1 9^
b1
,777
s/
.7c5o
LZaU
bj
./yy
1 .iil
S)4
.oLFy
1 .d/O
so
Qi O
.D 19
.5? /H
1 .HZO
«;r°
&b
.o^y
RIsCl
1 .4oo
1 .Uf u
Do
4 Ann
t.t>UIJ
D9
.CO/
r9 r a
1 .DD't
60"
RRR
»500
1 7**9
1 .#
61°
.Or V
1 804
62°
gg3
V70-
1 .881
63"
.891
.464
1.963
64°
.899
.438
2.050
65°
.906
.423
2.145
66"
,914
.407
2.246
67°
.391
68°
927
.375
1 47B
69°
^34
2.605
70"
94Q
2 747
71°
.326
72"
.951
.309
3.078
73°
.956
.292
3.271
74°
.961
.276
3.487
75°
.966
.259
3.732
76°
S70
.242
4.011
77°
.974
.225
4.331
78°
.978
.2pe
4.705
79°
.982
.I9t
5.145
80"
.985
.174
5.671
81"
.988
.156
6.314
82°
.990
.139
7.116
83°
.993
.122
8.144
84"
.995
.105
9.514
85°
,996
.087
11.43
86"
*998
.070
i4v30
87"
.999
.062
19.08
88°
.999
.035
28.64
89°
1.000
.018
mm
90"
1.000
.000
25-11
U.S. Nairal Fli^t Sulgeon's Manual
APPENDIX 25 8
DECELERATION PULSES AND EQUATIONS
Definitions:
= initial velocity in fps
Vf = final velocity in fps
S " stopping distance in feet
t > pulse duration in seconds (time to stop)
G ~ deceleration force in G
For the Case Vf = 0
I. RectangulaTPulse— GofUtantDecdraraition
TiirtB t
n. THangular IHibes CcMutanlly Qian^ng D«celeratiaoi
Case A — Incieadng Deceleration
G
time t
25-12
Case B — Decreasing Deceleration
- 1 - - . . I
Time t
Time t
in. Half -sine Pulse — Constantly Chan^ng Rate of Deceleration
Time t
Time t
mm
U.S. Naval n^t Satgedn^s Manud
For the Case Vf Q
I. lUctangidar Piudve— CkHMtant Decderatimi
G
Decel.
Time
Deceleration Force: G
v^v[
64.4 S
Pulse Duration: t
32.2 G
n. Triangular Pulses— Constantly Changing Deceleration
Case A — Increasing Deceleration
Decel.
Deceleration Force; G
4V^-2VoVf-2Vf=
96.6S
Pulse Duration: t
32.2G
Case B — Decreasing Decderation
Time t
mm
Ai^raft Accitlent SiitvirabiUty
Case C — Increasing and Decreasing Deceleration
G
Time t
m. Hatf-«ine Pulse — Constantly C3ian^g Rate of Deceleration
Time t
(from Crash Survival Investigators' School, 1976).
25-15
U.S. Naval Flight Surgeon's Manual
APPENDIX 25-C
SAMPLE CALCULATIONS OF LANDING AND CRASH FORCES
Example 1: Crash Deceleration Force
■"■ A T-28 crashes into a hUlside in stalled configuration. The Board establishes through
witnesses and wreckage examination that the plane crashed into a 10*^ incline at 66 mph, wings
level, 5*^ pitch-up attitude (relative to the horizon), digging a 40-foot trench in the earth,
18 in. deep. There was 6 in. of vertical compression to the bottom of the fuselage. The final
flight path angle was 15**. The actual impact angle was 25**. Find G-forces relative to the aircraft
floor. Consider the deceleration pulse to be triangular (increasing and decreasing deceleration)
and final velocity equal to zero (Vf = 0).
Step 1. Express all dimensions in appropriate units.
= Approach speed = 66 mph. x 1 .46 = 96.36 fps
S_ = Stopping distance on the hill = 40 ft.
Sj^ = Stopping distance perpendicular to the hill
= Depth of trench and vertical compression of fuselage
= 18 In. + 6 in. = 2 ft.
Step 2. Diagram the situation.
Vertical Fuselage = ,5 ft.
■V_ (ground speed)
25-16
Aircraft Acddent SMyabilitjir
Step 3. Calculations.
a) Sink rate, Vj^
sin 25°
96.36 f ps
sin 25° = .423
(friiin Appendix 25-A)
.423
96.36 fp$
= 40.8 fps
b) Ground speed, V_
cos 25" =
96.36 fps
V
.$06
96.^^
= 87.3 fps
(from Appendix 25-Al
c) Ctomponent of the G-force perpendicular to tiie liill, Gj, for a triangular pulse. A, Vf = 0
Gl
G
1
32.2 Sj^
(40:8 fp^^
32.2 X 2 ft.
25.9 G
(from Appendix 25-B)
d) Component of the G-force parallel to the hill, G -
vf
^= " 32.2 S_
25-17
U.S. Nflv«lJ*%bt Soifeon's Mmud
G_
(87.3 fps)''
32.2 X 40 ft.
5.9 G
e) Resultant G-force, G^, relative to the hill
Gj^=25.9G
5.9 G
G^^ = of + g[= (5.9)2 + (25.9)2
34.81 + 670.81
G^ = 26.56 G
G, 26.56
sin-'' .975 = 77*'
(from Appendix 25-A)
f) G-forces relative to the aircraft floor, G= g and Gj^^. Since the aircraft approached with a
5° pitch-up attitude, the G-force relative to the aircraft floor is at an angle 5° smaller than
the angle of the G-forces to the hillside. This becomes apparent from the following
diagram.
Horizontal
— — ^ ^'Jch Axis
to the aircraft floor is at 72°,
25-18
Aircraft Accident Survivabilily
To solve for G and G ■
=a J.a
G
sin 72" =
sin 72° = .951 (from Appendix 25~A)
V Gr = 26.6G
%a ^ia
Gf imQ
Ml
26.6 G
Gx, = 25.3 G
005 72'
G _a ®= a
% Mid
cos 72° = .309 (from Appendix 2S-A)
.309
G=a
26.6 G
G^3 = 8.2 G
Step 4. Conclusion:
G, = 25.3G
Xa
G^a = 8.2G
This was a survivable accident, but it is likely tliat vertebral fiQiumn ir^Mry was #e»nt that
could have impeded egress.
25-19
U.S. Nkval Flight Surgeon's Klttivial
Exampte 2: Carrier Landii^ ForciM
Using a hypothetical set of conditioiis, determine the decderation force during an arrested
landing of an F4 sdrcraft and the time of exposure to these forces
Indicated Airspeed (I. A.S.) - 155kt.
Carrier Speed of Advance (S.O.A.) = 20 kt.
Wind @ 355° relative = 10 kt.
Rollout on arrestment, = 275 ft.
Approach Sink Rate, > 900 fpm
Oleo strut and time compression of touchdown. By = 9 in.
Consider ttie arrestment deceleration pulse to be a half -sine pulse (a constantly changing rate of
decelt^ation) imd the final velocity equal to zero (Vf = 0).
Step 1. Express all dimensions in appropriate units,
1 55 kt. I.A.S. in 10 kt. wind 145 kt. ground speed
145 kt. srourtd speed in approach to a carrier with S.O.A. 20 kts. " 125 kt. ground speed
Vq = Ground speed = 125 kts. x 1.69 = 211.3 fps
Vy = Sink rate = 900 fpm -^60 sec./min. = 1 5 fps
Because of the mk rate, thore is a dij^t difference between the ground speed and the actual
approach speed of the aircraft. The approach speed can be calculated as follow:
Vq =211,3 fps
Vg- y +v| = 211.8fps
= Approach speed = 21 1 .8 fps
Sy = Oleo ftrut arid ttrsGompr^lbn * 9 in. = .75 ft.
25-20
Step 3. Calculations.
a) Horizontal component of the G-force, G|^, for a half -sine pulse, = 0
0.7854 •
Q = (irem Appendix 25-B)
" 32.2 Sh
0.7854 (211.8 fps)^
" 32.2 x 275 ft.
Gh =4G
b) Duration of G^, time G^
1.57 Vja^
time Gu = — (from Appendix 25-B)
~ 32.2- G^
time G^
1,57 (211.8fps)
32.2 x4G
time G^ = 2.6 sec.
25-21
U^. Bfwal Blight Surgeon's Mmual
c) Vertical component of ttie G-force, Gy, for a half -sine piibe, Vf ~ 0,
0.7854 Vv
Gy = 32.2 Sy
(from Appendix 25-B)
0.78B4 tlSftft)^
32.2 X. 75 ft.
7.3 Q
d) Duration of Gy, time Gy
time Gw =
^ 32.2 Gy
(from Appendix 25-B)
. ^ 1.57 (211.8fps)
= 32.2x7.3te
timeGy = 1.4 sec.
e) Resultant G-force, Gf, , when touchdown artd armtment occur limultaneously.
G„-7.3G
Gr - Gy + G^ = (7.3G)^ + (4G>*
Gu-4G
Gr = y 53.29 + 16
Gr - 8.3G
2^
' Acddentf Stih^aibiiitjr
tan^ =
7.3 G
1.825
4G
r
(from Appendix 25>A)
= 8.30 at 61.3'
|0
} -111 I
... I--,. -■. ...i.i't -ji
■ 1 ■ "1
Step 4. Conclusion.
G^^ = 4G for 2.6 sec.
Gy = 7.3Gfor 1.4sec.
Gr = 8.36 8161.3"
These forces are, of course, survivable.
■: n
)
25-23
U.S.. Naval FUght Siu^eon'; Manual
Examine 3: Multiple Deceleration Forces
A T-34 with simulated engine failure attempts wave-off at 500 ft., but the engine fails and
the aircraft continues an unpowered descent. The Aircraft Mishap Board reconstructs the
following sequence. The left wing snapped off a 9-inch-thick pine tree while crunching the wing
to a depth of 3 feet. Airspeed before impact was 105 kt. The aircraft continued airborne at
85 kt. ^before the right wing passed through and bent a 6-inch pine, putting a 2-foot-deep crunch
into its leading edge. Airspeed after the second impact was 60 kt., and the aircraft arced gently
to final impact in a swamp. The plane imbedded itself 8 feet «ito the muddy bottom which was
covered by 3 feet of water. Wreckage examination showed the engine to have been displaced
4 feet aft on final impact. Board members and consultants agreed that deceleration forces for
each of the three impacts were:
1st tree;
2nd tree;
swamp. Was this a survivable accident?
Step 1. Express all dimensions in appropriate units.
V^i = Airspeed before impact with tree 1 = 105 kt. x 1.69= 177.6 fps
= Airspeed before impact with tree 2 = 85 kt.x 1.69- 143.7 f PS
V^3 = Airspeed before impact in swamp = 60 kt. x 1.69 = 101 .4 fps
= Stopping distance at the first tree = tree diameter + wing crunch = 9 in. + 3 ft. = 3.75 ft.
Sj = Stopping distance at the second tree = tree diameter + wing cruncii = 6 in. + 2 ft. = 2.5 ft.
S3 = Stopping distance in swamp = mud depth + water depth + engine displacement
= 8ft.+3ft. + 4ft. = 15ft.
Step 2. Diagram the situation.
25-24
Aircraft Acddent Survivability
Step 3. Caiculations.
a) &fDrce in impact with tree 1 , , for a triangular pulse,
96.6S
(from Appendix 25-B)
I,..
G, =
4{177.5 fpsr -2(177.5 fps) (143.7 fps) -2(143.7 fpsl"
9a6x3.75ft
= 93.1 G
Ml
I 1
b) G-force in impact with tree 2, Gj, for a triangular pulse,
= 32.2 $2
, =^ 0.
(from Appendix 25-B)
(143.7 fps)'' - (101.4fps)^
32.2x2.5 ft.
Gj = 128.8G
c) G-force in impact in the swamp, G3, for a triangular pulse,
,Vf = 0.
4 via
G =
3 ge.esg
(from Appendix 25-B)
25-25
D.S. Navjd Fli^t Swfeonls Mannal
^ 4(101.4 fps)^
3 ~ 96.6x15 ft.
Gg = 28.40
Step 4. Conclusion.
G, = 93.1 G
Gj = 128.8G
G3 = 28.4 G
This was not a survivable accident. Impacts in the -G^ direction occurring simultaneously with
each tree strike exceed the survivability hmits given in Table 25-1 by a substantial margin; both
crewmen would have perished upon hittmg the first tree. To emphasize the importance of
velocity, re-do the problem if the exit speed from the first tree was 100 kfei. instead of 85 kts.
ITie force associated witli the first impact drops from 93.1 G to a survivable 24.6 G, however,
the impact with the second tree would then be 227.1 G, which is not survivable.
25-26
n
Aircraft Accident Sitttli^abtiitjr
Exaatf^e 4: Cairier Ramp Strike
An A'7 making a eittJfor landing approach gets low in the groove and strikes the ramp
without a siidt rate. I.A.S, in the approach was 130 kt. to a carrier steaming at 25 kt. into a 5 kt.
wind. The Accident Board established that the ramp strike put a 6 -foot-deep crunch into the
underside of the aircraft as it hit nose high. The relatively intact fuselage without landing gear
slid up the deck decelerating from 90 kt. at the beginning of the slide to 75 kt. as it passed over
the angle after 600 feet of travel. The aircraft came to rest in the water after an estimated
300 feet of airborne trajectory from a deck height of 75 feet and 60 feet of trasvfel through the
water. Ascertain if the impact forces involved were survivable because the pilot was not
recovered.
Step 1. Express all dimensions in appropriate units.
1 30 kt. I . A.S. in j5 kt. wind = 1 25 kt. ground speed
125 kt. graund speed in approach to a carrier withi S.O.A. 25 kt. = 100 kt. landing speed
Vq = Landing speed = 100 Itt.x 1.69 = 169 fps
= Speed crossing tlie decl< = 90l<t. x1.69 = 152.1 fps
= Speed passing over the angle = 75kt. x 1.69 = 126.8 fps
i \ Vf = 0 (aircraft resting in water)
Sr = Stopping Distance at ramp impact = aircraft crunch = 3 ft.
Sq = Distance traveled on the deck = 600 ft.
Syy = Stopping Distance in the water = 60 ft.
Step 2. Diagram the situation.
Carrier S.O.A. 25 kt.
)
25-27
U^. Naval Flight Su^eon'js Manual
Step 3. Calculations.
a) G-force in ramp impact, Gp . Assume a triangular pulse
4V3-2VoVp-2Vd
96.6
(from Appendix 25-B)
Go =
4(169 fps>^-2(169 fps) (152.1 fps) -2(152.1 fps)^
9a6x31t
Gr = 57.2 G
b) Duration of , time Gp
2(Vo-Vd)
timeGR = ^
(from Appendix 25-B)
time Gpi =
2(169 fps -152.1 fps)
32.2x57.2G
timeGp = .02 sec.
c) G-force in slide over the decit, Gq. Assume a rectangular pulse I I.Vf^^O
2 2
'D 64.4 Sd
(from Appendix 25-B)
Gn =
(152.1 fps)^- (126.8 fps)2
64.4x600 ft.
Gn = 0.2 G
25-28
d) Duration of Gq, tifne Gq
time Gq =
32.2 Gd
£.0 (f ptn ApFiendix 25-B)
time Gp =
152.1 fff -126.8f ps
time = 4 sec.
. : r '> '■■'. , •i'»l'..n> c»).
e) G-force in water entry, Gyy. Assume a triangular pulse.
4v;
Guu =
96.6
4(126.8 f(»)2
W 96.6 x 60 ft.
{from Appendix 25-B)
G„ = 11.1 G
f) Duration of Gy^, time G^
time Gyy =-
2V,
32,2 Gyy
(from Appendix 25-B)
2(126.8 fps)
*""'°W =32.2x11.1G
time Gyy = 0.71 sec.
25-29
U^. Nnral Flj^t Surgeon's Manwil
Step 4. GoiK^fflon.
Gff « f7.2G fior 0.02 sec.
6q -> 0.2 G for 4 sec.
6^ = 1T.lGfor0.7t sec.
The impact forces incurred at the initial ramp strike were probably not survivable. The
amount of crunch to the aircraft is a critical Sgvire. If the Board decided that the crunch -was
6 ft., that figure at the ramp would change from an uhsurvivable 57.2 G to a survivable 28.6 G,
and more crunch would attenuate even more of the forces. Accurate Board input for the
calculations is critical.
In the most technical sense, calculation of the water impact forces should be via
trigonometric functions, setting up a trian^e based on known distances, figuring the water entry
ani^e, and substituting velocities in the same triangle for final G calculation.
a) Cilculation of the water impact angre
75 ft.
sin 6
75
300
-.25
(from Appendix 25-A)
sin-' .25=14.5*'
b) Calculation of tlie sink rate, X
stnic rate = V^^
25-30
126^ fpt
- Wnl4.f°)».25
31.7 fp> sink rate
c) Calculation tlw vartical component, Gy , for the water impact
4Vi
OA ac
(from Appendix 25-B)
r .. 4(31.7fps)^
^ 96.6 X 60ft.
Gw - 0.7G
dt Caiculation of the horizontal component, G^, for the water Impact
Gu "
4V.
H fut ft e.
(from Appendix 2S-B)
, ^ 4(1 26.8 fps)^
" 98.6 X 60ft.
Gh - 11.1G
e) Crieulation of the UKuttant G, G^ , for the water impact
Gw - .7G
25-31
U.S. Naval Flight Surgeon's Manual
Using + =
Gr = (11.1)^ + 1.7)^
Gr = 11.12G at 14.5°
This cdculation eon&ms that for such shallow an^es of water entry, the trigonometric
approach involves extra work for the same answer.
25-32
o
CHAPTER 26
AIRCRAFT ACaOENT AUTOPSIES
Introduction
Administrative Considerations
Field Procedurea
Autopsy
Accident Causation
Role of the Fli^t Surgeon
References
Bibliography
Major aviation accidents in the Navy and Marine Corps in 1976 involved 101 fixed-wing
aircraft and 27 helicopters, with a dollar cost in the hundreds of millions. These losses represent
a significant erosion into the Navy's readiness and the nation's assets. There is understandable
concern, and considerable effort is being devoted to minimizing aviation hazards and losses.
As the Navy continuously attempts to develop effective programs to prevent accidents and
to protect aircrewmen, program designers frequently turn to available medical data to find
correct solutions, only to be frustrated by the realization that much of the relevant data are not
observed and not recorded. Those attempting to design better support and survival equipment,
such as helmets, life-preservers, and escape systems, often ask specific and important questions
about the pathogens^ of injury and the precise mechanisms of death. Far too often, these
questions remain unanswered. The objective of this chapter is to examine aviation accident
autopsy procedures in a manner which wiU surest to the FUght Surgeon and to the pathologist
alike potentially rewarding avenues for solutions to these important problems. This chapter does
not repeat the technical and professional information currently available to pathologists
concerning the performance and interpretation of a postmortem examination. The intent is to
dwell only on j^ose facets of ;die ^i^l^^ j^I^^ tend to be pecuUar to the aviation accident
autopsy.. ,
Aviation i6MBm pathology is defined by Mason (lM2) as '*the appUcali^ df^i^Mg aftfl
tecliniqiies of pathology to the comprehensive undeitttaiiditig of aircTiift accident causes and
genesis." To achieve a comprehensive understanding of Euch an event requires that thorou^y
■It- :^>■,■'.<^■f^<
a<< >tit
261
U.S. Naral Fli^^t SiugeonV Manual
studied autopsy material be analyzed and interpreted in the context of well-defined operational
and environmental considerations. Combining these two types of information should lead to a
correct explanation of the etiology of the accident event. Although this is seldom accomplished
- in routine investigations, the validity of this method remains unchallenged.
Adnuiustrative Considerations
Because many Navy aircraft accidents occur in civilian jurisdictions, it is necessary to
understand the requirements of state and federal investigators. Custom, usage, and the law have
defined the state as the appropriate govemment unit to deal with decedents' affairs. St*te
officials must derive information needed to establish the cause and mmmer of death, the
identity of the decedent, flie pieaence or abs^ice of foul play, and tfie requirements for
administering estate, wills, and insurance payments. The Federal Government, on the other
hand, is obliged to regulate air traffic, define safety standards in aviation, operate public aircraft
safely and efficiently, study accident causes to prevent recurrence, and maintain the security of
federal property. If one compares the requirements outlined above, which are neee^arily
incomplete, it becomes obvious that the differences should logiciffly result in different methods
m^ gttsk for the conduct of an aviation autopsy, depending on whether it is intended to satisfy
the state or the federal purpose. It is important for a Flight Surgeon to understand that the
different requirements placed on the local coroner mean that his examination, in all likelihood,
will hot address those issues posed by the Navy in its safety investigation.
An excellent exanple of tfie dissimilarity between state and tedetsi purposes is found in a
state law which requires that "The Coroner shall hold an inquest upon the dead bodies of such
persons only as are supposed to have died by unlawful means." Such a law, administered even
by the most sympathetic and careful state official, would reasonably be interpreted to preclude
postmortem examination of aircraft accident victims based on the presumption that such events
generally are not caused by unlawftd means.
The most practical way to manage investigation problems on civilian terrain is to begin by
consulting the local legal officer representing the naval district or the supporting Naval Air
Station. Informal contacts with physicians in the civilian community, which may include the
local coroner or medical examiner and the local pathologist, may provide obvious solutions and
courses of action. OPlSfAtlf^Bt 3750.6K estldflishes tfiat a naval activity's pre-accident plan
must include arrangements for insuring the immediate retrieval of remains. These considerations
are commonly ovtarlooked and are a frequent source for delay, confusion, and acrimony which
can interfere with effective study of a case.
Aircraft Accident Autopsies
There is a statutory basis for federal authority to conduct autopsies. In Chapter 20, Title 49,
U S Code Section 701, there is a provision for the National Transportation Safety Board "to
examine the remains of any deceased person aboard the aircraft at the time of the aecid^t »ho
dies as a result of the accident and to conduct autopsies or such other tests thereof as may be
necessary to the investigation of the accident; provided, that to the extent consistent with the
needs of the accident investigation, provisions of local law protecting religious behefs with
respect to autopsies shall be observed."
The Armed Forces Joint Committee on Aviation Pathology has proposed a change to the
U S Code which would provide the authority for miHtaiy departments to exarame thereiisains
af any deceased person aboard an aircraft at the time of an a«eito and to conduct autopsies or
such other tests as might be necessary to investigate the accident. It is possible that definite
developments in the law may take place within the next few years. Until that time, the best
working remedy is to anticipate local jurisdictional problems and to plan coordinated efforts
with the involved officials to satisfy the needs of both the state government and the Navy.
Frequently, a copy of the autopsy protocol, ddtttfered to the appropriate OffiMal, is
adequate to aiow the retrieval and examination of remains itt a dviHan junction.
For accidents occurring on federal reservations in which there is exclusive federal
jurisdiction, BUMEDINST 6510 Series, Article 17-2, Manual of the Medical Department, md
Paragraph 703 of OPNAVINST 3750.6K define the authority to perform aUto^As onittflitary
occupants fataUy injured in aircraft accidents. The Decedent Affairs Manual, WMBB SW
Series and lh^ BUMED 6320 Series, way slsobeusetel glides.
Field Procedures
Procedures to be followed by a Fli#it Swrgeon as a member of m accident mvestiption
team are described In Chapter 24, Aircraft Accident Inve$^tion$. This covers the requirements
imposed on the Fli#it Surgeon. The immediate collection of information at the crash site which
can be used to support the later postmortem examination is essential.
The biggest problem to be faced by a Flight Surgeon in the first few hours following a crash
is one of documenting the relationships at the crash scene before the body is moved. There is an
initial^ and very understandrfjle, emoional response by the first individuals on the crash scene
to do something about the body. It is quite difficult for most individuals to begin any kmd of
systematic examination of crash issues while the deceased pilot remains in the cockpit.
CharacteristicaUy, the body is removed from the cockpit and taken to Some other location
26-3
U.S. Naval Flight Surgeon's Manual
before the investigation has any organization at aU. Frequentiy, it is a day later before the
prineipal accident investigators arrive, and, by this time, much of the information to be gleaned
from the pilot^s remains has been lost. Such losses include the location and spatial relationship
of the remains to the aircraft structure or systems components, prominent terrain features and
areas of fire. Therefore, to the extent feasible, a Flight Surgeon should attempt to documenl the
relationships at the scene before the body is moved. Sketches, photographs, and a careful
examination of the aircraft with the body untouched can prove invaluable in supporting
evidence found later during autopsy procedures. Of particular import here is documentation of
the mechamcs at the scene that eould explain injury. For example, a diagram which shows the
location of the body, of various components of the aircraft, and of a postimpact fire can help
later m differentiating burns which occurred after the accident from those which might have
occurred m the cockpit prior to the crash.
Autopsy
A postmortem examination of the victim of an aircraft accident should foUow an orderly
and well-organized plan. If the most meaningful results are to be obtained, autopsy procedures
and techniques should be developed and reviewed well in advance of their actual use. The Flight
Surgeon diould have knowledge of pathology techniques which are usuaUy capable of answering
questiona posed by the Aircraft Mishap Board (AMB). He should be aware of the types of
aircraft operated by the local commands and then assigned missions, the facilities and
consultants avaUahle from local federal and civihan sources, such as crime laboratories, research
units, etc., the requirements of applicable state and federal laws and agreements, and the
requnements for graphic documentation to allow later interpretation of autopsy findings as new
accident findings become available.
The direction of the pathology inquiry may be guided by three principal objectives. These
are (1) di^osis of pre-existing dise^e conditions, (2) the description of all injuries and an
analysis of their pathogenesis, and (3) cataloging of all observations which m%ht serve to better
understand the accident cause and sequence. Examples of tiiese considerations are included
below.
Identification of remains is usuaUy accomplished in naval aircraft accidents with relative
ease because the number of aircraft occupants is usuaUy smaU, the available operational data
concerning the aircraft and its occupants are abundant, and dental records are characteristically
available and accurate. It should be noted, however, that reliable identification of remains
IS essential to correlation of autopsy findings with accident cause and sequence. Even
when the intent is to autopsy crewmembers only, medical examinations of all remains may
26-4
Aircraft Accident Autopsies
be required to estabUsh which subjects are in fact crewitteinbers. Details of these
techniques are described by Spitz and Fisher (1973).
Pre-Existing Disease
The search for pre-existing disease conditions is a routine part of any autopsy examinatf&n.
However, in an aviatidn mish^. It WarraTife fecre^d littentlon. Here the objective is not just to
desert m hsm. eonditioh of #e deceased, but to search for conditions which might have
caused incapacita^n itt fl^ Ot whidi might have led to a reduction in sensory or motor
capacities.
In looking for pre-existing diseases, one of the classic questions is "What role did ischemic
heart disease play in postulated pilot incapacity?" Because coronary artery disease is so common,
there frequently wffl be some description in an autopsy protocol concerning coronary
atherosclerosis. The objective is to specify the extent of coronary occlusion and its
morpholo^C consequences and to indicate the Ukelihood that this might have resulted m either
transient or permanent pathophysiologic states.
It is not reUable or useful to define a coronary letoii MepettdeuMy of a cotiiprehensive
analysis ^fieoperaaonal circumstances. Stt A a "dtoi©al histoiT "*ffe'|W»tly provides evidence
that clearly preeliSdBS Uie etiologic relationship of established lesions. For example, a scenario in
which the pilot of a troubled aircraft describes by radio the detailed progression of mechanical
difficulties which preclude both continued flight and safe egress, makes it untenable that the
accident was caused by sudden incapacitation, even in the presence of tiie most impressive
morbid anatomy. Furthermore, it is useful to remember that a flight might be completed and
indeed many have been completed, without accident* ewn when *e pilot was incapacitated.
The differential diagnosis of the aberrant behavior related to an accident logicaUy includes
psychological and aviation considerations as well as organic disease. These are easUy overlooked
or misiftterpreted by pathologists who do not have experience in aviation.
Description of Injuries
All injuries sustained during the accident should be described in detail. This is true whether
or not a specific injury might have contributed to the death of the subject. Obviously, the first
order of business is to describe those injuries which could have been fatal. It is most important
to identify, with as much certainty as possible, the exact cause of death. However, it also is
quite important to note all other injuries so that realistiG assessments can be made of the safety
design of the aircraft and of the effectiveness of specific items of protective equipment.
26-5
U.S. JNaval Fli^t Surgeon's Manual
Medical Officer's Reports (MOR's) frequently do not provide an adequate characterization
of injuries. The MOR may report, for instance, that the pilot suffered a fractured ulna and that
the fracture wm caused by impact forces. This is sufficiently vague to be essentially meaningless
for later use by investigators. It is more helpful to describe and interpret the injury as a
transverse fracture of the ubia at a specific location mediated through blunt forces appfied to
the antenor aspect of the forearm. This can then be correlated to ^ecific cockpit structures
adjacent to the arm of the pilot, as he was observed in the cockpit following the impact. In
^ort, the description of injuries must be as detailed as can reasonably be done and should
iHchide any observations and interpretations concerning the Ukely pathogenesis of the injuries.
There are also patterns of injuries which may serve to define events and injury mechanisms.
Knowledge of these patterns can be usefiil to a Flight Surgeon as he interprets and assists in the
autopsy examination. For example, bilateral subconjunctival hemorrhage in the absence of
other ocular injuries characteristically suggests premortem negative acceleration in the z-axis
Distribution of Injuries
Certain injuries tend to occur frequently in aircraft accidents, simply because of the nature
of the force environment and mechanisms found in such events. A Flight Surgeon should
understand this distribution, but he should also recognize that the characteristics of these
mjunes may change as aviation missions change and as one deals with different types of aircraft.
Unusual injuries representing a deviation from the expected may signal a previously
unrecognized pathogenic mechanism or a peculiar event important to an understanding of the
accident sequence. To monitor such events, the Naval Safety Center analyzes afl aviation
accident injuries as functions of anatomic site invohfed and aircraft type. This provides a means
of comparing injuries that occur in one aircraft type with injuries occurring in a different type.
Differences in injury patterns may also be compared with the averaged injury tabulation for all
types of aircraft. Significant differences invite attention to systematic failures that predispose to
the subject injury. A chart of injury distribution according to anatomic regiops provides a useful
reference. Table 26-1 summarizes over 7,000 injuries identified in the medical investigations of
Navy/Marine Corps aircraft accidents between January 1969 and July 1977.
In a similar manner, it is possible to tabulate the kinds of injury reported and to identify the
proportions of the total injury experience contributed by each diagnostic category (Table 26-2).
The data tend to reflect injuries that are of major significance and readily and conclusively
identifiable, but they do not consistentiy relate to the cause and mechanism of death.
26-6
Aircraft Accident Autopsies
Table 261
DistrOtufion of Navy/Marine Gorpi Asvia^dtin AfrnMnt
Injuries by Aaatoime Eeg^ons
Anatomic Region
Percent of Total
Injuries Reported
Total Body
15.0
Head and Necic
24.0
Torso
20.1
Upper Limb
19.6
Lower Limb
21.3
Table 26-2
Distribution of Navy/Marine Corps Aviation Accident
Injuries by Diagnostic Categories
Diagnosis
lament of Total Injuries Reported
Fracture" Oisloeation
22.8
Contusion
16.1
Laceration
12.3
Abrasion
8.3
Thermal Burn
7.9 1
Sprajjiy^min
7.0
Multiple Extreme Injuries
6.3
Amputation/Avulsion
3.6
Hemorrhage
2.4
Perforation/Rupture
2.1
Concussion
1.1
Crushing
1.1
Decapitation
1.1
lei^ilifi^iis
7.3
Head and Neek Injury
Thst evaluation of head and neck injury is an area of particular concern and obvious
importance during an autopsy examination. The head/neck area is especially ^sceptible to
26-7
U.S. Naval fli^f Su^eon'e Manual
itqury from the forces of an aircraft accident, and the nature of head injuries is sudl ihat acute
incapacity and fatal consecjuences can be anticipated. Twenty -four percent of all injuries affect
the head and neck, even though their surface area and mass represent a lesser proportion of the
body. A truly random distribution of injuries is not hkely in an aircraft accident. Cockpit and
cabin structural configuration, methods of restraint, common patterns of accident acceleration,
and the nature of protective devices mfluence this injury distribution. The design of such
devices, including protective hehnets, can logically derive from detdled observations of
pathogenetic meschanisms of head and neck injury. Hie aviation accident experience is the
medium throu^ which one may make unique and valuable assessments of such mechanisms.
The use of Medical Officer's Reports to answer the question, "What is the nature of the
head injury, and how did it occur?" is limited by the quality of the data. Frequently, the MOR
contains a description of helmet condition, a notation that the skull was fractured or that there
were lacerations over portions of the head, and that the head injury was due to impact.
Information such as this is not sufficiently detailed to be useful. One needs more information
about the sequence of accident events, a better definition of the applied forces, and some
indication of the order of magnitude of accident impact forces. Knowledge of the mechanism of
injury is vital to most remedial efforts.
Severe injuries can be sustained by the head and tiie cervical region which are not easily
noted on routine examination. For example, a preliminary examination might indicate the cause
of death was an impact force apphed to the lower thoracic region, resulting in broken ribs,
severe lacerations, and extensive hemorrhaging. In fact, however, such injuries might well be
eurvivable, with the actual cause of death being an unnoticed transection or laceration of the
spinal cord at the base of the brain. When a number of injuries are sustained at the same time, it
is very important to identify those which explain the mechanism of death.
The correct identification of head and neck injuries provides invaluable data for designers of
aviation protective clothing and equipment. At this time, Navy research and development effort
is being directed toward the development of a new helmet for aircrewmen. The helmet is to
allow better head movement during air-to-air combat and to provide even more protection than
afforded by current hehnets. Should it be stronger, lighter, ftilly-restrained, or fran^le? One of
the best ways to answ^ these questions is with information developed through meticulous
autopsy examination in which head and neck injuries are described in detail and carefully
related to the crash circumstances.
There are four mechanisms for head and neck injury which predominate in adation
accidents. The autopsy examination should evaluate each of these as a possible cause of death,
26-8
Aircraft Acddeftt Autopsies
even diough other injuries obviously were suffieieiit in iiemselves to be fatal. The following
sections describe these mechanisms.
Head-Neck Inertia. When the body is moving at a given velocity and is suddenly decelerated,
whether by impact or by ejection and dynamic ram air pressure, there can be an inertia of the
head/neck/hehnet/mask complex which cm dites® a seviip diffierential deceleration of tiiis
complex with respect to the «eit Off the body. There may be a flexion so Aat the head is moved
forward or backward suddenly with consequent hyperextension of the neck and either injuries
to the bone and muscle around the neck or a pulling of the central nervous axis. In order to
demonstrate at autopsy that this has occurred, it is necessary to make a dissection of the central
nervous system so that the brain stem, the medulla oblongata, and the cervical spinal cord are
not altered in the dissection. That block of anatomy has to be viewed undistorted. A posterior
dissection into the spine and occipital skull is recommended to expose the relevant tissues and
to deteWBine whether there are lacerations, hemorrhage, or other physical evidence of
mechanical trauma «t the site. . i ; • |'
(
In the aft-hyperextension case, hemorrhage may be noted in the para-spinal muscle system.
With forward hyperflexion or hyperextension, fractures may be noted in the anterior vertehrial
bodies and in oihm iBUScle groUps. If ite btain stem is maintained intact, gross laceratic^ns of
that part of the brain stenj or the vessels covering the brain stem may be seen on 8e«#ia-
Capillary hemorrhages within the brain stem also may be noted.
Direct Impact. Direct impact injury is found when an aviator's helmet receives a direct blow
during an accident. Under circumstances where the impact delivers sufficient energy to separate
the hehnet and then to disrupt Ife&ikull ind brain beweath it, eaase.<rf .de«Eaiis. obivi«U8Jte#
%\m apparent that the ener^^baorbing qualities of the helmet were exceeded. In such a case,
the postmortem examination is largely a matter of documenting the injuries and attempting to
estimate the magnitude of the force which caused the helmet to separate. Typical injuries to be
noted include epidural, subdural, and subarachnoid hemorrhages, and avulsions, lacerations, and
hemorrhage of the brain itself.
Translated Impact. A more elusive, and somewhat speculative, mechanism for head and
neck injury can be used to account for cases in which the helmet remains intact, but a fatal
injury is sustained nonetheless (Figure 26-1). In such an instance, the hekmt has apparently
distributed imparl f bites tiSffosmfly dtar the sfefll so as to fe&q) issiic preikwe pfet uifflt are
and coiiseqiJent tissue damage, at a niliiiinMtti- H<>Wfe^, ikt fact that the accident was fatal
would indicate that the acfatafl: dfetribution of impact forces did not provide adequate
protection.
26-9
U.S. Naval Fli^t Surgeon's Manual
bone)
Figure 26-1. Distribution of fatal impact forces with helmet remaining intact
(drawing by Norman Nusinov, Armed Forces Institute of Pathology).
If one conceives of the human skull as being a bit akin to an old Roman arch, or a Roman
bridge, a case em he made that imjpact force is not uniformly distributed but instead is simply
translated from one part of the head to another. The engineering principle behind the Roman
arch was that force applied at the top was earned by the form of the curved structure to the
pillar or base, where it could be supported better than at the top. Within the skull, a similar arch
can be identified. It is comprised of the calvarium, the lateral temporal bone, and the petrous
ridges of the temporal bone (Figure 26-2). This curved structure has as its base the part of the
fifculi where the brain stem resides, the posterior part of the body of the sphenoid bone, and the
basilar portion of the occipital bone.
A characteristic finding in autopsies with head injuries in which helmets were worn is a
fracture occurring just anterior to the petrous ridge of the temporal bone and extending toward
the brain stem (Figure 26-3). Frequently, the base of the skull at the juncture of the posterior
and middle compartments becomes almost bivalved, so that one can actually move it as a bivalve
structure, indicating the significance and depth of the fracture at the anterior limits of the
26-10
Aircraft Accident Autopsies
petrous ridge. A simliar lesion is described by Spitz and Fisher (1973) as a hinge fraettn^, TMs
section of bone is rather thin and apparently is more mechanically susceptible to discontinuity
as forces are applied. It appears, then, that when energy is applied to an upper portion of the
helmet it may simply be translated through the "arch" of the skull and delivered to the base of
the brain, resulting in the fracture frequently seen at the anterior hmits of the petrous bone.
Energy appUed there may become lethal immediately because vital centers for respiration and
other autonomic functions are located in the brain stem.
Calyorium
The situation thus may exilt wttiWS '»t atito{i^ 'sh©W^'k^M4 that is itomple^^^ iWttct
externally and a hehnet which has sustained some damage. The assumption may be made that
the helmet was effective as designed because the damage is in the helmet and not in the exterior
of the head. However, this may be misleading. The translation of energy, imparted at the helmet
and transmitted through the "arch" of the skull, may have consequences in the brain stem
which are quite Ifeiisfl. fe ari ^omaly which can easily be overlooked durii^ #
postmtiitiem examination. . j< . i. i
26-11
U.S. Nmd Flight Surgeon's Manual
Figure 26-3. Redistributed fracture to floor of middle cranial fosaa (hdmeted injury)
(drawing by Norman Nusinov, Armed Forces Institu|J%#i|^itology).
Hangman's Noose Analogy, l^e infmor edge of an aviatot*B helmet, when visuahzed as part
of the continuous circle completed by the nt^e ite^ aai lBie-cJimstr^Vfonns aloop that can
be likened to a hangman's noose. The analogy might be further extended to include the lesions
made about the neck by the straps or the edge of the helmet, parallehng the abrasions and
contusions that might be associated with a rope having encircled the same structures. When the
knot is situated at the side of the head (subdural), such a hangman's noose produces fractures of
the base of the sknll, tending to extend bitej»|i6ritlly throu^ the basisphenoid. When tihe knot
is situated anteriorly aaad befie^tfa the chin (aibmental), &e hangman's noose causes a fracture
dislocation at the axis (Wood-Jones, 1913). CJharacteristically, the posterior arch is fractured
and, interestingly enough, the odontoid process is not involved.
One interesting and compelhng aircraft accident investigated by the Naval Safety Center,
Norfolk, Virginia, served to emphasize the practical s^pjication of this tiieoretical exercise
(Gplpigdo^ 1974). A Navy A-4 jet aircraft experienced difficulties in fli^t which caused the
pilot to eject at an altitude, attitude, and airspeed that were within the operating envelop of
4he ejection seat. Supported by a fully -blossomed, functioning parachute, however, the pilot
26-12
reached the ground severely injured flnd died shortly after the accident as a result of a transverse
laceration of tiie cervical spinal eord.
The investigation established that the energy responsible for the fatal lesion was transmitted
through the helmet and its inferior edge into the posterolateral neck. A vertebral dislocation
of C-2 on C-3 resulted, which in turn severed the spinal cord. The essential mechanism of injury
involved the apphcation of blunt force to one side of the helmet, causing it to rotate about the
pilot's head in such a way that the opposite side of the helmet was forced inferiorly and
medially into the adjacent heck region. Similar observations had prompted an earlier
modification of the helmet to incorporate a thicker protective edge roll. The actual helmet
involved in this case is pictured in Figure 264. Note that the damage to the helmet is slight and
hardly commensurate with the significance or severity of the associated injury. It is of ten tajsitly
assumed when a Mmet which has been subjected to a large impact force exhibits oidy di^t
damage that the head which it is designed to protect should remain proportionally secure. This
unfortunate case illustrates that nothing could be further from the truth.
Figure 24-4. The helmet involved in the prodneioit qI eer
. plOipred radiplogiicany
The pathology itself was distinctive in that a dislocation without fracture occurred at the
C-2/C-3 level of the cervical spine. A roentgenographic study of the specimen is reproduced in
Figure 26-5. A laminectomy was performed post mortem to expose the spinal cord. Hlgtoid^c
26-13
U.S. Naral Ili^t Surgeon's Manual
sections made through the C-2/C-f vertebraii confirmed that no fracture was present, despite
common observations in the literature that fracture is the usual, if not an invariable
accompaniment, of such severe dislocations (American Academy of Orthopaedic Surgeons
Symposium, 1969).
Figure 26-5. Roentgenographic views of the autopsy specimen demonstrate the vertebral dislocation
at e-2/C?3.' Note that no evidence of fracture is present (Colangel*), i$74).
It is especially interesting that "hangman's fracture" has been fairly recently defined as a
bilateral avulsion fracture through the neural arch of the axis, with or without fracture
'dislocation of the second cervical vertebral body upon the third (Schneider, Livingston, Cave, &
Hamilton, 1965). The concept of the "cervicocranium" as an entity constituted by the cranium,
the atlas, and the axis su^ests that this functional segment above C-3 tends to move as a single
unit, in dislocation as wdl as in flexion, extension, and rotation. The implied mechanical
weakness at C-3 or the junction of the cervicocranium with the lower cervical spine makes it a
likely site for dislocations in injuries sustained by mechanisms resembling that presented in this
particular accident. . " "
Blunt Trauma to &e Lungs
Mason (1962) notes that decelerative pulmonary lesions of the severity seen in aircraft
accidents should be more akin to blast injuries than to those sustained in motor accidents. When
a heavy blunt force is apphed to the lungs, there is extensive hemorrhaging, probably as a result
of internal shearing forces. Mason reviews the experimental hterature describing specific
patterns of hemorrhaging found with deceleration forejes. Unfortunately, there is less
26-14
information available on the pattern of lung damage t@'b©fottsd.4a#r<HF#fciB«dP^
damage of this type>iaft |)e noted in over 50 percent of all fatalities.
An important point in dealing with lung trauma is to be able to separate accident damage
from evidence of pre-existing lung pathology. As the vasculature is torn during an accident,
blood enters pulmonary alveolae, as does serum. The serum in alveolar spaces can resemble
edema fluid, thus presenting a confusing picture to a pati^D^ W1^«{3l^fl|lidiiSvthe»^4s a
direct result of the aceileffli or as part of an earUer disease process can only be determined by
iwieisfing lh#. location of lacerations in lung tiwe, >o^er patholop© fmdiugs m.the
cardi©i©lpiii#ory QoWplejEs Wid the clinical history.
Accident Causation
fhi responsibiUty for assigning causes to an aircraft accident rests with the fuU Aircraft
Mishap Board. The FUght Surgeon and the pathologist with whom he might work are
responsible for contributing information which wUl aid the Board in arriving at the correct
causes. However, it can be of considerable help to the Board if -ttieFli^it Surgeon includes Ms
speculations regarding causative elements. In general, it can be said that a fine cUnical sense and
considerable experience are required to di»i»titiate among possible causes that might be
suggested by anatomical findings. Nonetheless, any conclusions, however tentative, reached by
the Fli^tSiiiieop. should be included as part of hi^ ., , „ , ,
While speculations concerning accident causes are encouraged, conaderable 4im^i
should be given to each in order to be certain that tiie pathological interpretations being
discussed are consistent with the circurastaneei of the accident and findin|8 feom oi}i©r
of investigation.
A Flight Surgeon has definite responsibilities in tiie event of an aircraft accident involving
Navy personnel. If these responsibihties are met fully, a Fbght Surgeon can make a real
conti-ibution toward understanding the causes of aircraft accidents, to continu^
improvements in protective clothing and equipment, and to an evfe*.imp roving safety tMW'
in naval aviation.
In summary, the postmortem examination of an accident victim can provide important
information on the causes of an accident, information not obtainable through any other source.
However, for the autopsy examination to be most effective, there are three issues which must be
faced.
26-15
U.S. Ninrtd Flight Surgeon's Manual
As stated previously, thftrcf are Many instrumentalities of government to be dealt with in
handling a fataUty, particularly when the accident does not <i«;<Ji|r on federal property. It is
particularly important for a naval activity's pre-accident plan to include arrangements for
insuring the immediate retrieval of remains. These arrangements can be expedited by
establishing liaison with local authorities and physicians prior to any accident. Provision should
also be made for consultations with the legal officer representing the naval district or the
supporting Ninml Aii" Station.
The FUght Surgeon should participate to the fullest extent possible in the aviation autopsy
examination. The pathologist may be an outstanding examiner with a wealth of experience in
performing routine postmortem examinations, but it is rare indeed when his experience includes
expertise in handUng remains from aircraft accidents. The Flight Surgeon makes an important
contribution, therefore, by defining the questions that diould be asked in the examination. The
pathologist rdies on the Fli^f Su^on and his understanding of aviation Operations, current
aircraft, protective equipment, and specific aircraft Systems to jtosure fcit tihe^^t questioris are
addressed.
The requirement for a Flight Surgeon to participate in the deliberations of an Aircraft
Mishap Board is contained in the OPNAV Instruction of the 3750.6 series. Ch^ter 24, Aircraft
Ae<:ident Inmst^ations, elaborates on the various duties of tiie Pli^t Surgeon as a m^ber of
this board. A few words ate In order here, however, concerning tiie disposition of issues which
may arise during the autopsy examination.
There is a requirement that the Aircraft Mishap Board and the Flight Surgeon, working
togelh», address any problem that arises in the medical investigation which is of significant
import. The Aircraft Accident Report and The Medical Officer's report must be complementary.
This does not mean that they must say the same thing. It is interpreted to mean that the same
issues must be treated, and evidence must be presented that the two sides have communicated
on medical issues of significance and that each has developed its position addressing that
problem. If for some reason the Flight Surgeon feels that medical issues are not being given
adequate attention in dehherations of the full Aircraft Midiap Board, he can note this in the
Miedical Officer's Report, or he can communicate directly vfilk the Nftval Safety Center. He does
bear the responsibiUty for seeing that medical findings that may have relevance in determining
accident causation or in improving issues of aviation safety are given full weight in the
conclusions of the Aircraft Mishap Board.
26-16
Aircraft Accident Autopsies
References
American Academy of Orthopaedic Surgeons symposium on the spine, Qc^dasd, November 1967'.
. it. Um'. CV, Moaby Co., 1969y p. 29.
Colm^o, E J. The CBrvieO<3!BafflMa aild the aviator's protective helmet. U.S. Navy Medicine, 1974, 64, 32-34.
Department of the Navy, Office of the Chief of Naval Operations. Navy aircraft accident, mcident, and ground
accident reporting procedures (OPNAVINST 3750.6 series).
Mason, J.K, Aviation accident pathology. London: Bwtterworfli and Co., 1962.
Scteeider, R.C., Livingston, K.E., Cave, Aj.E., & Hamilton, G. "Hangman's fracture" of the cervical spine.
fmmd of NeuTomgery, 1965, 22,(2).
Spitz, W.U., & Fisher, R.S. Medical invest^ation of death. Springfield, 111. : Charles C. Thomas, 1973.
Wood-Jones, F. The ideal lesion produced by judicial hanging. Lancet, 1913, J , 53.
Bibliography
AndwsOB, W,A.D: Pathology (5th ed.). St Louis: C.V. Mosby Co., 1966.
Blackwood, W., et al. (Eds.). Greenfield's neuropathology (2nd ed.). Baltimore: The Williams and Wilkins Co.,
1963.
Mason, J.K., & Reals, W,J. Aerospace pathology. Chicago, HI.: Cbllege of American Patholo^fits' Foundation,
1973.
Randel, H.W. Aerospace medicine (2nd ed.). Baltimore: The WiUiams and Wilkins Co., 1971.
Reala, WJ. (Ed.). Medical investi^ition of aviation accidents. Chicago: El.: College of American Pathologists,
1968.
26-17
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APPENDIX A
AN HISTORICAL CHRONOLOGY OF AEROSPACE MEDICINE IN THE U.S. NAVY
8 Oct 1912 The first physical requirements for prospective naiiial Umttflfg^dtfiiied in Bumu
of Medicine and Surgery Circular Letter 125221.
8 Nov 1921 Five Navy medical officers report to the Army's School for Flight Surgeons at
Mitchell Field, Long Island, New YbA,
29 Apr 1922 Navy's first five Flight Surgeons designated. Graduates are: Lieutenants
Victor S. Armstrong, Louis Iverson, Julius F. Neuberger, Page O. Northmgton,
and Carl J. Robertson.
1922 Lieutenant Bertram Groesbeck becomes the first naval medical officer to
complete flight training and be designated a naval aviator. Upon eolttldetion of
flight training, Groesbeck reports to the Army 'iAoi^ fot W0t Surgedrrs,
gBadfiattg on Apiil I9i3.
1923 Lieutenant Victor S. Armstrong, MC, USN, becomes the first Chief of the
Aviation Medicine Division, Bureau of Meitteane and Surgery.
14 Nov 1924 Chiefs of the Bureau of Aeronautics and the Bureau of Medicme and SUrgSry
agree upon the ijualifieatiom {cw J.e8^ation as a naval Flight Surgeon. These
included a three-month course at.%f U.S. Army School of Aviation Medicine
and three months of satisfactory service with a naval aviation unit prior to
designation. The requirement that a medical officer so qualified also make
flights in aircraft was limited to emergend^ and to the desire of the officer.
18 Jan 1927 First course of instruction for FUght Surgeons to be given in the U.S. Navy is
initiated. The three-month course was eondueted at the Naval Medieal Sehool,
Washington; D.C., located in the N^vd dbssmtoa^v
28 July 1932 Research into the physiological effects of high acceleration and deceleration, as
encountered in dive-bombing and other violent maneaveMf is initiated by lite
Bureau of Medicine and Surgery. This pioneer research pointed to the need for
anti-G or anti-blackout equipment and was conducted at the Harvard University
School of Public Health by Lieutenant Commander John R. Poppen, MC, USN.
A-1
IT.S. Nayal Fli^t Surgeon's Manual
24 Oct 1933 Development of the first anti-blackout program is initiated by the Naval
Aircraft Factory to develop and manufacture a special abdominal belt in
accordance with specifications prepared by Lieutenant Commander
John R. Poppen, MC, USN. This belt was to be used by pilots, in dive-bombing
and other violent maneuvers, in order to protect against blackout.
5 Jan 1935 Lieutenant Commander John R. Poppen, MC, USN, is the first Flight Surgeon
to be assigned to the Naval Aircraft Factory to conduct work on the physiologic
aspects of the research and development projects being carried on at the
factory.
24 Aug 1939 A medical officer is detailed to the Bureau of Aeronautics for the purpose of
establishing an aviation medical research unit.
20 Nov 1939 The first instruction in aviation medicine at the Naval Air Station, Pensacola,
Florida, begins with the reporting of nine reserve medical officers to the Medical
Department. Thus began the Navy School of Aviation Medicine. The first class
was graduated on 20 January 1940 as Aviation Medical Examiners after a
60-day course of instruction.
15 May 1940 The first medical air-evacuation flight is coadueted when an XSOC-1 aircraft,
piloted by Lieutenant G.L. Heap, transferred an injured seaman from the
destroyer USS Noa, at anchor in the Delaware River, to the Naval Hospital,
Philadelphia, Pennsylvania.
July 1940 The "1,000 Aviator" study is initiated by the Harvard Research Group,
sponsored by the Civil Aeronautics Authority, the National Research Council,
and the U.S. Navy. This group conducted a complete physiological and
psychological study on a total of I0S6 students and mstruetors at Pensacola. The
studies included electrocardiograms, electroencephalograms, somatotyping and
cardiac workups. Follow-up study on this original study of students and
instructors hag continued at intervsds through the years. Responsibility for this
program is a function of the Naval Aerospace Medical Research Laboratory,
Pensacola.
30 Nov 1940 First Naval Flight Surgeons graduate from the School of Aviation Medicine.
1941 Captain John R. Poppen, MC, USN, becomes the first military Flight Surgeon to
hold the position of President of the Aeromedical Association.
24 Feb 1941 A new building is dedicated to house the expanding Naval School of Aviation
Medicine at Pensacola. Prior to this time, the school occupied quarters in the air
station dispensary.
An Historical Chronology of Aerospace Me€itttfe ia the tJ.S. l!*a\ry
June 1941 First altitude training unit is establishea at Navid' A
ittdoGtrinate all aviation personnel in the use of oxygen and oxygen equipment,
aild in the physiological and psychological effects of anoxia. Other units were
rapidly established at major air training hases. The designation of these units
was later changed to Aviation Physiology Training Units.
18 May 1942 Chief of Naval Personnel authorizes breast device to be worn by officers of the
J^edliQrt Cprps wJbL(0, qpialified as Naval Flight Surgeons.
2?Jtiae l942 Work initiated by the Controlled Elements Group, Aeronautical Materials
Section of the Naval Aircraft Factory, on the development of high altitude
pressure suits.
19 July 1942 First pair of FUght Surgeon wings presented to Captain Frederick Ceres, MC,
USN. The wings, fashioned by the NAS Dental Department, are presented by
Captain A.C. Read, Commandant, NavfflA^r Station, Pehsdebk.
10 Qet 1^42 Secretary of the Navy authorizes naval Flight Surgeons to be included as "flying
officers" entitiing them to draw flight pay while detailed to duty involving
flying. Prior to this time, FUght Surgeons drew at the discretion of
^ ■ --^ their commanding officer.
5 Nov 1942 Commander Eric E. LUjencrantz, MC, USNR, is the first Navy Flight Surgeon to
be Wted ti W^M^^ accident. Commander laljencrantz was killed in the crash
of a dive-bomber while acting as observer in an aeromedical res^lireh project.
17 Jan 1943 Tests conducted at NAS San Diego by pUots flying F4U-ls report that the
anti-blackout suits developed at the Naval Ancraft Factory increased their
tolerance to the accelerations encountered in gunnery runs and., otJier maneuvers
by three to four Gs,
30 Nov 194S The AeroMedical Department, under a naval Flight Surgeon, estabUshed as a
separate group within the Naval Air Experimental Station, Philadelphia, with
increased responsibilities in the area of physiological factors involved in
aeronautical equipment and aircraft design.
March 1944 First night vision training unit estabUshed at Naval AuxiUary Air Field,
Charleston, South CaroUna, to determine the advisabiUty of using a CaxmMm^
developed night *ii&n Wdri# In' » p6^mk The need for adequate
night vMon trMtiing of aviation personnel was becoming of greater concern due
to the increasing use of night fighter aircraft. The first demonstrations to the
U.S. Navy medical and aviation personnel were made by Wing Coraniander
K.A. Evelyn, RCAF, at Charlestown, Rhode Island, in the spring of 1944.
A-3
U.S. Naval Flight Surgeon's Manual
1 Sept 1944 Mary F. Keener, first designated Aviation Physiologist, comes on active duty.
12 Dec 1944 Three evacuation squadrons commissioned in the Pacific from air-sea rescue
squadron elements to provide evacuation services.
17 Mar 1945 Responsibility for evacuation of wounded personnel assigned to the Naval Air
Transport Service.
3 Apr 1945 Commodore John C. Adams, MC, USN, becomes first practicing Flight Surgeon
promoted to flag rank. This occurred following a distinguished career in aviation
medicine, more than ten years of which was in the position of Chief of the
Division of Aviation Medicine, Bureau of Medicine and Surgery.
January 1946 Training of Aviation Medicine Technicians and Low Pressure Chamber
Technicians begins at the Naval School of Aviation Medicine. Previous
instruction had been done at local di^ensaries.
August 1946 The Aeromedical Department, Naval Air Experimental Station, Philadelphia,
redesignated as tiie Aeronautical Medical Equipment Laboratory, mth a Flight
Surgeon as superintendent in charge.
14 Aug 1946 Aeronautical Medical Equipment Laboratory, Philadelphia, begins human and
equipment mvestigation relating to the development of an ejection seat to be
used for emergency escape from aircraft, utilizing a 150-foot ejection seat test
tower obtained from Great Britain.
15 Oct 1946 The School of Aviation Medicine in Pensacola, previously a part of the station
Medical Department, officially designated by the Secretary of the Navy as the
U.S. Naval School of Aviation Medicine and Research, with its own officer in
charge. This officer was Captain Louis Iverson, MC, USN.
May 1949 First ejection seat training is given to naval pUots utilizing tiie Martin-Baker
ejection seat test tower at tiie Aeronautical Crew Equipment Laboratory,
Philadelphia.
24 May 1949 Aviation Medical Acceleration Laboratory, Naval Air Development Center
JohnsviUe, P^sylvania, estabUshed by Chief of Naval Operations with its
misaon to perform research and development in the field of aviation medicine
pertaining to the human centrifuge. Captain J.R. Poppen, MC, USN, was tiie
first laboratory director.
9 Aug 1949 First use in tiie United States of a ifflot qection seat for an emergency escape is
made from an F2H-1 Banshee exceedmg 500 knots in the vicinity of
Walterboro, South Carolina.
A-4
An Hktorical ChrondogyofAeEOSpSee Medicine U.S. Navy
1950 Helicopters used for the fi»8t time in the air evacuation of wounded patients in
Korea.
January 1951 First class of Aviation Physiologists come onboard School of Aviation Medicine.
March 1951 First ejection seat trainer deUvered to the Naval Air Station, North Island,
San Diego, Califomia. This tritiiflg dMce, whi6h iMulates the ejeotiUti seat itt
the Grumman F9F fighter, was designed to provide a realistic means of training
pilots in the correct procedures and characteristics of seat ^ection and to
, pro^pifttfi confidence in the use of this method of escape.
9 July School of Aviation Medicine commissions a separate command with a medical
officer as commanding officer. Captain Leon D. Carson, MC, USN, first
commanding officer.
1 Aug 1951 The HG-1 (high acceleration) catapult transferred from Naval Aircraft Factory,
Philadelphia, to the Aeronautical Medical Equipment Laboratory, Naval
Experimental Station, iMadelphia. This gave the laboratory a imluable res^uccfc
tool for use in the study of restraint methods Wi^d eqWipRI^
occupants from injury in aircraft crashes.
If J«tne l9S2f Aviation Medicine Acceleration Laboratory at Naval Air Development Center,
Johnsville, commissioned, and its human centrifuge with a 50-foot arm and
capable of producing accelerations up to 40 Gs put into operation as a research
tool for investigating the reistion of ll|raf| tci the accdi#«tft At encountcared in
flight at various temperatures and altitudes.
1 Apr 1955 Incentive pay authorized fi(& IOw*pre8suiiB «hamte to^de ini^
and human test sul^ectB participaitof in leseaffi^ fift^'^
30 June 1955 The first operational full-prefflure suits, a Navy development, placed in aervice
to protect aviators at hi^ altitudes in the event of loss of cabin fHressi^Ztttion.
, _ 'Phe aiiit'Was diligtied, to protect men while in a space environment
8 July 1956 School of Aviation Medicine, Pensacola, s^proved for . two years formal
residency training in aviation medicine by the American Board of Inventive
Medicine.
19 Dec 1956 Chief of Naval Air Training establishes the Special Board of Flight Surgeons.
This permanent board of medical officers appointed at the Naval School of
Aviation Medicine, Pensacola, "To provide prompt and hi^y competent
professional ^i^'»t^iir of the physical quahfications of aviation trdaees and to
^{Ksdife pfticessing of those not qualified to continue training." Senior member
of the board is the commanding officer of the School of Aviation Medichie.
A-5
f «S> Nwat fli^t Surgeon's Manual
I' Feb'lti? BiaitdMaat ^waad^iF Prank H. Austin, Jr., MC, USN, completes test pilot
training at Naval Air Test Center, Patuxent River. He was the first Navy Flight
Sui^eon to qualify as a test pilot.
3Q, Apr 1957 Naval Aviation Medieiil Center at PettMcola commissioned, combining under a
single command the clinical, training, and research functions of the Naval
School of Aviation Medicine and the Naval Hospital, Pensacola. First
commanding officer is Captain Lester McDonald, MC, USN.
June 1957 Johnsville human centrifuge hooked into the analog computer "Typhoon" so
that dynamic control simulation is possible and subjects in the centrifuge
gondola can actually "fly" the device, simulatmg the fli^t characteristics of
any selected type of aircraft.
28 June 1957 A successftil ground-level ejection demonstrated at Naval Air Station, Patuxent
Elver. Aviation Medicine Branch of Service Test participated in this demonstra-
tion.
15 Nov 1^S7 Incentive pay authorized for human test subjects in thermal stress experiments.
March 1958 Bioastronautics Test Facility put into operation at Air CreV Equipment
Laboratory, Philadelphia. This faciHty permits the confinement and isolation of
up to six human subjects under simulated space capsule conditions for
indefirate periods of time at any simulated altitude from sea level to
100,000 feet.
June 1958 Human Disorientation Device installed at the Naval School of Aviatita
Medicine, Pensacola. This device offers a means of stuc^ring the causes of verti^
and disorientation in aviators and provides a means for evaluating possible
protective procedures.
8 Aug 1958 Lieutenant R.H. Tabor, MC, USN, completes a 72-hour simulated flight in the
pressure chamber at the Aviation Physiology Training Unit, NAS Norfolk while
wearing a Goodrich light-weight full pressure suit. During this time he was
subjected to altitude conditions as high as 98,000 feet.
13 Dec 1958 The Na\y -trained squirrel monkey "Gordo" (Old Reliable) makes a sub-orbital
fli^t into space. He successfully withstood the fli^t and re-entry, as evidenced
by the telemetered data, but was lost when the nose cone in which he was riding
sank due to failure of the flotation gear. Scientists at the School of Aviation
Medicine were responsible for the design and fabrication of the bio-capsule in
which "Gordo" rode and for its instrumentation.
(^'\ An Historical Chronology of Aeroapace Medidad Id Hie U.S. Navy
28 May 1959 Miss Baker (Tender Loving Care), a squirrel monkey trained at the School of
Aviation Medicine, becomes the &8t pritfiates to^«B<^:r#.filib'^orMtal space
flight. Upon her return to earth, she was set up in an "apartment" at the school
where she remained until 1971. In 1971 she was transferred to the Army's space
museum in Huntsville, Alabama.
June 1959 The seven Mercury astronauts participate in centrifuge simulations of Atlas
rocket launches, re-entries, and abort conditions ranging up to plus 18G
(transverse), at the Aviation Medical Acceleration Laboratory, Johnsville. These
dmulations were conducted on the largft hflsjMaai^ centrifuge located at that
facility. >< i u}/ V
4 May 1961 The Navy's high altitude Itfloon flight, Stral^L-afe ^^t)v5,^asfeeawls from #ie deck
. «f *#ie m^im #IS Amkfmt^t^ m fltiWde of 1 1 3 ,000 feet and a flight duration
of 8.9 hours. The flight carried Commander Malcolm D. Ross as pilot and
Lieutenant Commander Victor A. Prather, a naval Flight Surgeon, as medical
investigator. The occupants rode in an open framework gondola and were
proteef^d''#6tri Ihd ^tftg' tf ie^^ barometric pressure by their Navy-
developed full pressure suits. This successful experimental flight was marred by
the death by drownii^^f ^ejiteiiprt Coj^ipder feather during flie recoveiy
) phase of the flight. , • ..
22, July 1964 The Coriolois Acceleration Hatform (CAP) and vestibular unit, dedicated at the
; . ..>i^^4of Aviatioii,.M§diQine. ,
14 May 1965 Dedication of new buildings (Buildings 1953 and 1954) for the School of
Aviation Medicine.
2d June 1965 Lieutenant Commander Joseph P. Kerwin, MC, USN, naval Blight Surgeon and
naval aviator, selected as ane of #e fet phyaician-fistronauts in the U.S. space
2 Aug 1965 The first flarii blindness indoctrination trainer device, 18F22, installed at
Marine Corps Air Station, Beaufort, South Carolina. This device subjects the
subject to a simulated nuclear blast hght flash and demonstrates the resulting
temporary blindness that occurs without prof^^tfon. It SK^'tWionsbfatfeS tfeff
prbWctl&n Slfewd by flash bUndness protective devices.
Sept 1965 Lieutenant Paul A. Furr, MSG, USN, is the first Aviation Physiologist to qualify
al' i'^ie pmMie^ SWd to be desij^ated as a naval parachutist. Furr is qu^fied
to wear the Navy and Mfoitte iSbrps Parachutist insignia.
A-7
U.S. Naval Flight Surgeon's Manual
2 Sept 1965 The Naval School of Aviation Medicine is redesignated the Naval Aerospace
Medical Institute.
24 Sept 1965 Captain Mary F. Keener, MSG, USN, an Aviation Physiologist, is the first
woman officer on active duty to be promoted to the rank of captain in the
Medical Service Corps, U.S. Navy.
10 Jan 1966 The Secretary of the Navy approves the designation of Aviation Experimental
Rsychologists and Aviation Physiologists as flying officers and orders them to
duty involving flying.
7 Apr 1966 Ensign Gale Anne Gordon, MSG, USNR, completes the course of training in
aviation ^perimental psychology at the Naval Aerospace Medical Institite. On
28 March 1966 Ensign Gordon became the first woman to solo in a naval
aircraft.
11 Apr 1966 Captain Msaty F. Keener, MSG, USN, is elected Vice President pf the Aerospace
Medical Association during its 38th annual convention, becoming the first Navy
woman ever to hold that office.
12 Apr 1966 The Assistant Secretary of the Navy officially autho^;^ weaSang of by
the Navy's Aviation Physiologists and Aviation Experimental Psychologists.
1 July 1967 The Aerospace Crew Equipment Laboratory (formerly the Aeronautical Crew
Equipment Laboratory) officially transferred from the command of the Naval
Air Engineering Center, Philadelphia, to the command of the Naval Air
Development Center, Johnsville, Pennsylvania, and redesignated the Aerospace
Crew Equipment Department.
7 July 1967 The first change in the visual acuity standards for carrier pilots since before
World War II is made when Service Group One naval aviators are allowed to fly
with a visual acuity of 20/50 corrected to 20/20 provided glasses are worn while
in i^tual control of aircraft.
25 July 1967 Ttie Naval Aerospace Medical Institute begins conducting a complete
radiological examination of the vertebral column of aU personnel in the fli^t
training program, as part of the program to reduce possible causes of back
injuries due to an emergency ejection escape from naval aircraft.
19 Jan 1970 The Naval Aerospace Medical Research Laboratory is designated a component
command of the Naval Aerospace Medical Institute. First officer in charge is
Captain Newton W. Allebach, MC, USN.
A-8
An Historical Chronology of Aerospaieife MBiSdiie-ln lkt U.S, Navy
21 Mar 1974 The first female Flight Surgeons graduate from the Navy's Flight Surgeon
School at the Naval Aerospace Medical Institute. The first female i%ht
Surgeons were Lieutenants Jane McWiJliams and Victoria Voge.
1 July 1974 The Naval Aerospace Medical Institute becomes a command under the newly
formed Naval Health Sciences Education and Training Command.
The Naval Aerospace Medical Research Laboratory, a component command of
the Naval Aerospace MecKcaL Institute, becomes a m^^M''Uttimmi under
BCMED's Researeh and Development Command. PirSt cdmmanding officer is
Captain Newton AUebach, MC, USN.
5 May 1975 The first class of Aviation Medical Officers (AMOs) reports to the Naval
Aerospace Medical Institute for four weeks of training. AMOs are assigned as
flight Surgeon expanders to aviation activities.
Summer 1976 The repatriated prisoner of war study, being conducted on former Navy and
Marine Corps prisoners of the Vietnam conflict, becomes the responsibility of
the Naval Aerospace Medical Research Laboratory. Since January 1974, the
responsibility for the study had been a function of the Naval Aerospace Medical
Institute.
August 1976 The flr^t naval Flight Surgeon/Family Practitioners are gratified ai tfite 'JIa^al
Aerospace Medical Institute. The first graduates were lieutenant GoromandeK
Leon J. Davis and Barry Mullin.
Biblit^aphy
Adams, J.C. Personal interview, 1976.
Adams, J.C. Developments in aviation medicine. In The khtory of the medical department of the United State$
Navy in WoHd War 11 (NAVMED P-5031, Vol.1). Washington, D.C.: D.S. Government Printing OiBee,
1953.
Barr, N.L. Night vision training. In The history of the medical department of the Steves Naey in Wofld
. JKji? H (BIAVMED P-i081, VoL 1). Washington, D.C. : U.S. Government Printing Qffts^ llSSi * " " ' * '
Benford, R.J. Doctors in the sky. Springfield, El.: Charles C. Thomas, 1955.
Courtney, M.D. Bureau of Medicine and Surgery internal memorandum, 1 September 1967.
Hodge, W. A history of aerospace medicine in tfie U.S. Navy. U tlkiiiMal flight suTf^oriit mMMt
Wadiington, D.G.: U.S. Govetnmmt Printing Office, 1968.
Kellum, W.C. PerBonal interview and Uireirculated letter, 1976.
Naval School of Medicine. CONTACT (newsletter). Pensacda, Fl., Vols. 1-17, 1941-59. ' "
West, V.R., Every, M.G., & Parker, J.F., Jr. History of the n4«il «arospace physiology prograna* Ih ESS.«»«i>I
mrospace physiologUt's maaml (NAVAIR 00-8OT-99). Philadelphia, Pa., NawJ- Air Engmeering Center,
Septemher 1972.
Williams, N.E. Hi^ altitude training. Ik The history of the medical department of the United States Navy in
IMd War JJ (NAVMED P-5031, Vd. 1). Wadiington, D.C:: U.S. Government Printing Office, 1953.
Yanqnsll, Q.p. P«»onal uncirculated letter, 1976. , ...
A-9
U.S. Naival Fligbt Stirgeon's Manual
NAVY FLIGHT SURGEONS ACHIEVING
POSITIONS OF LEADERSHIP AND COMMAND
Head of Aerospace Medicine
Bureau of Medicine and Surgery
LT Victor S. Armstrong, MC, USN
Chief, Section on Aviation Medicine
LT R.P. Henderson, MC, USN
Chief, Section on Aviation Medicine
CDR Robert G. Davis, MC, USN
Chief, Section on Aviation Medicine
LCDR John R. Poppen, MC, USN
Chief, Section on Aviation Medicine
LCDR Jod J. White, MC, USN
Chief, Section on Aviation Medicine
Captain Louis E. Mueller, MC, USN
Chief, Section on Aviation Medicine
Rear Admiral John C. Adams, MC, USN
CI lie I', Section on Aviation Medicine
In 1944 title changed to Assistant Chief for Aerospace Medicine
Rear Admiral B. Groesbeck, Jr., MC, USN
Assistant Chief for Aerospace Medicine
Rear Admiral W. Dana, MC, USN
Assistant Chief for Aerospace Medicine
Captain Oran W. Chenault, MC, USN
Assistant Chief for Aerospace Medicine
Captain M.fl. Goodwin, MC, USN
Assistant Ciiief for Aerospace Medicine
Captain H.C. Hunley, MC, USN
Assistant Chief for Aerospace Medicine
Apr 1923 -Jan 1925
Jan 1925 - Sept 1926
Sept 1926 - May 1929
June 1929 ~ Oct 1929
Oct 1929 - May 1933
May 1933 - Apr 1937
Apr 1937 -Dec 1946
Jan 1947 - Apr 1952
Apr 1952 -Aug 1957
Aug 1957 - July 1959
Oct 1959 - Feb 1963
Feb 1963 - May 1964
A-10
An Historical Chronologf of AerospaSs Sfefflcfae% the U.S. Navy
Captain W.M. Snowden, MC, USN
Assistant Chief for Aerospace Medidine
Captain Leonard P. Jahnke, MC, USN
Assistant Chief for Aerospace Medicine
etpft^ ^^wajt A. Jtmes, MC, USN
A^tant Chief for Aerospace Medicine
Captain Frank H. Austin, Jr., MC, USN
Asfflstwit Chief for Aerospace MWcMe
In July 1974 title changed to Director, Aerospace Medicine Division
Captain M.G. Webb, Jr., MC, USN
Director, Aerospace Medicine Ditiaaon
May 1964 - July 1968
Aug 1968 - June 1971
Aug 1971 - Dec 1973
Jan 1974 -Sept 1976
Oct ).976 - Present
Officer iii Otai^
Naval School of Aviation Medicine and Research
Captain FredWck Geres, MC, USN*
Captain Bertram Groesbeck, MC, USN*
Captfdn Louis Iverson, MC, USN*
Captain Bruce V. Learner, MC, USN**
Captain Wilbur E. KeUum, MC, USN
Captain Leon D. Carson, MC, USN
!Jtjl/'l938
June 1942
Nov 1944
Jan 1947
July 1947
Feb 19S0
- June 1942
- Nov 1944
- Jan 1947
- July 1947
- Feb 1950
- July 1951
Commanding Officer
Naval School of Aviation Medicine and Research
Captain Leon D. Carson, MC, USN
Captain James L. HoUand, MC, USN
Captain JuUus C. Early, Jr., MC, USN
Captain Lwigdon C. Newman, MC, USN
Rear Admiral Lai^don C. Newman, MC, USN
Captain Qifford P. Phoebus, MC, USN
Captain Henry C. Hunely, Jr., MC, USN
July 1951 -
June 1952
July 1954 ■
July 1957
Aug 1960 -
Oct 1960
Aug 1964
June 1952
- July 1954
-Jtilyl9S7
-Aug 1960
Oct 1960
Aug 1964
- Sept 1965
*ADDU from NAS Pensacola where assi^ed as Senior Medical Officer.
**Fir8t person to recdve ordeis tor duty as Officer in Cha^.
A-11
vs. Niwd Flight Surgeon's Manual
Commanding Officer
Naval Aerospace Medical Institute
Captain Henry C. Hunely, Jr., MC, USN Sept 1965 - May 1967
Captain Joseph W. Weaver, MC, USN May 1967 - July 1969
Captain Marvin D. Courtney, MC, USN July 1959 _ 1973
Captain Robert C. McDonough, MC, USN July X972 - June 1974
Captain Henry S. Trostle, MC, USN j^jy 1974 _ pr^gg^t
Navy Presidents of Aerospace Medical Association
*Captain John R. Poppen, MC, USN I94I _ 1942
Rear Admiral John C. Adams, MC, USN I946 _ 1947
Captain WUbur E. Kellum, MC, USN I949 _ 1950
*Rear Admiral B. Groesbeck, Jr., MC, USN I953 ^ 1954
Captain Ashton Graybiel, MC, USN I957 _ ^953
Rear Admiral James J. Holland, MC, USN 1961 _ 1952
Captain Frank B. Voris, MC, USN 1966 - 1967
Captain Ralph L. Christy, MC, USN I97O _ 1971
Captain Frank H. Austin, Jr., MC, USN I976 _ 1977
Deceased.
A-12
APPENDIX B
AEROSPACE MEDICINE BILLETS
AdBiiral
1. Naval Aerospace & RegioiM Medical Center, Pensacola, FL
Captains
1. NAF Branch Clinic - Andrews (NNMC, Bethesda, MD)
2. Naval Medical Research & Development Command, Bethesda, MD
3. Naval Medical Research & Development Command, Betjkiesdt, MD . , .
4. BUMED, Director, Aerospace Medicine Division
5. BXJMED, Head, Aerospace Medicine Operations Branch
6. BUMED, Head, Aerospace Medicine Technical ©ranch
7. BUMED, Head, Physical Quahfications
8. Naval Air Systems Command, Washington, DC
9. HQ U.S. Marine Corps, WrtlSlfton, DC
10. HQ FMF Pacific, HI
11. HQ FMF Atlantic, Norfolk, VA
12. First Marine Aircraft^lwfvttan^Wa - Wing Me^csfl ittfcer
13. Second Marine Aircraft Wing, Cherry Point, NC - Wing Medical Of&mt
14. Third Marine Aircraft Wing, El Toro, CA - Wing Medical Officer
15. Chief of Naval Operations (OP-098E), Washington, DC
16. Naval Ht^SfStal, (BiWf Polttts 3!*C - Direct®r ©f ©Meal Services
17. Branch Clinic, MCAS,Kaneohe, HI (NRMC, Hawaii) ,
18. Branch Chnic, MCAS, El Toro, CA (NRMC , Long Beach)
19. NASA, Houston, TX
20. NAS, New Orleans, LA
21. Naval Aerospace & Regional Medical Center, Pensacola, FL
22. Naval Aerospace Medical Institute, Pensacola, FL — CO
23. Naval Aerospace Medidal Institute, Pensacola, FL - Academic Dep.
24. Naval Aerospace Medical Research Laboratory, Pensacola, FL — CO
25. Naval Safety Center, Norfolk, VA
26. NADC, Warminster, PA
27. COMNAVAIRLANT, Norfolk, VA - Force Medical Officer
28. COMNAVAIRPAC, San Diego, CA - Force Medical Officer
29. Branch Qinic, NAS, Miramar, CA (NRMC, San Diego)
30. Branch Clinic, NAS, North Mand, CA (NRMC, San
31. Naval Regional Medical Center, Corpus Christi, TX - CO
32. MCAS, Yuma, AZ
B-1
UjS. Naval Flight Surgeon's IVfiUnial
Commanders
1. Naval Hospital, Annapolis, MD
2. NATC, NAS, Patuxent River, MD
3. Branch Clinic, MCDEVEDCOM (Naval Hospital, Quantico, VA)
4. Armed Forces Institute of Pathology , Washington, DC
5. Naval Hospital, Beaufort, SC
6. Branch Clinic, NAS, Chase Field, TX (NRMC, Corpus Christi)
7. Branch Clinic, NAS, Dallas, TX (NRMC, Corpus Christi)
8. Branch Clinic, Agana (NRMC, Guam)
9. Branch Clinic, NAS, Barbers Point, HI (NRMCL, Hawaii)
10. Branch Clinic, NAS, Jacksonville, FL (NRMC, Jacksonville)
11. Branch Clinic, NAS, Cedl Field, FL (NRMC, Jacksonville)
12. Third Marine Aircraft Wing, El Toro, CA
13. Branch Clinic, NAS, Point Mugu, CA (NAVHOSP, Port Hueneme)
14. Branch Chnic, NAS, Moffett Field, CA (NRMC, Oakland)
15. Braach Clinic, NAS, Alameda, CA (NRMC, Oaadand)
16. Bfaiich Clinic, NAS, Whiting Field, FL (NARMG, ?ensaeola)
17. Branch OBnic, NAS, Meridian, MS (NARMC, Pensacola)
18. Naval Aerospace Medical Institute, Pensacola, FL (Six Billets)
19. Naval Aerospace Medical Research Laboratory, Pensacola, FL
20. Branch Oiiiic, NAS, WiUow Grove, PA (NRMC Philadelphia)
21. NADC, NAF Warminster, PA
22. Branch Clinic, NAS, Norfolk, VA (NRMC, Portsmouth)
23. Environmental & Preventive Medicine Unit, #2, Norfolk, VA (AMSO)
24. Environmental & Preventive Medicine Unit Satt BfegOj CA (AMSO)
25. Branch Clinic, NTC, Kenitra (NRMC, Rota» Spain)
26. Branch Clinic, Iwakuni (NRMC, Japan)
27. USS AMERICA (CV-66)
28. USS CONSTELLATION (CV-64)
29. USS CORAL SEA (CV-43)
30. USS EISENHOWER (CVN-69)
31. USS ENTERPRISE (CVN-65)
32. USS FORRESTAL (CV-59)
33. USS INDEPENDENCE (CV-62)
34. USS J.F. KENNEDY (CV-67)
35. USS KITTY HAWK (CV-63)
36. USS LEXINGTON (CVT-16)
37. USS MmWAY (CV41)
38. USSNIMrrZ(CVN-68)
39. USS RANGER (CV-61)
40. USS SARATOGA (CV-60)
B-2
Lieutenant Comdaiinden
1. Branch CUnic, MCAS, Quantico, VA (N AYHOSP^ OyfeTOjdiO^
2. Branch Clinic, NAS, Brunswick, ME (NRMCL, Portsm«»i% . ;
3. MATVAQWINGPAC, Whidbey Island, WA . -
4. First Marine Aircraft Wing, Okinawa
5. Second Marine Aircraft Wing, Cherry Point, NC (Three BiUi^ts) .
6. Third Marine Aircraft Wing, El Tore, CA (Three Billets) " ."
7. Branch Clinic, NAF, Detroit, MI (NRMC, Great Lakes)
8. NAVHOSf , Guantaiiaiiio, Ciiba
9. Branch Clinic, NAS, Atlanta, GA (N^C, Jacks&Mvaie)
10. CVW-1, Cecil Field, FL
11. CVW-3, Cecil Field, FL
12. CVW-6, Cecil Field, FL
13. CVW-7, Cecil Field, FL
14. CVW-8, CecU Field, FL
15. CVW-17, Cecil FieW,FL
16. Naval Station, Keflavik, Iceland
17. BranchClinic, MCAS, Santa Ana, CA (NRMC, Long Beach)
18. VX-4, Point Mugu, CA ,
19. COMNAVSUPPFORANTARCTICA, Point Mugu, CA
20. NRMC, Memphis, TN
21. Branch Chnic, NAS, Fallon, NV (NRMC, Oakland)
22. NARU, NAS, Alameda, CA
23. VA-122, Lemoore, CA
24. First Marine Aircraft Wing DET A, Iwakuni, Japan
25. Exchange Officers, USAF • "
26. Naval Aferospaee Medifflne Institute, Pensacola, FL (Three Billets) '
27. Naval Aerospace Medicine Residency, Pensacola, FL (Twelve Billets)
28. Naval Aerospace Medical Research Laboratory, Pensacola, FL
29. Branch CHrac, NAS, Lakehurst, NJ (NRMC, Philadelphia)
30. NADC, Warminster, PA (Two BiUets)
31. Branch Clinic, Oceana, VA (NRMC, Portsmouth)
32. VRF-31, NAS, Norfolk, VA
33. Branch Clinic, NAS, Bemuda (NRMC, Portsmouth)
34. Naval Safety Center, Norfolk, VA
35. Environmental & Preventive Medicine Unit #2, Norfolk, VA (Three Billets) (AMSO)
36. Environmental & Preventive Medicine Unit #5, San Diego, CA (AMSO)
37. Naval Hospital, Roosevelt Roads, PR
38. Naval Hospital, Rota, Spain
39. Branch CUnic, NAS, North Island, CA (NRMC, San Diego) ■ : ^ : '
40. ASWWINGPAC, San Diego, CA
41. Branch Clinic, El Centro, CA (NRMC, San Diego) . , ,
42. Branch Clinic, NAS, Cubi Point, RI (NRMC, Subic Bay)
43. Naval Hospital, Lemoore, CA '
B-3
U.S. Nard Fli^t Surgeon's Mmaal
Lieutenants
1. Naval Hospital, Patuxent River, MD
2. VQ-4, Patuxent River, MD
3. VX-1, Patuxent River, MD
4. NARU, NAF, (Andrews), Washington, DC
5. Naval Hospital, Whidhey Island, WA
6. NARU, Whidbey Island, WA
7. VA-128, Whidbey Island, WA
8. VAQ-219, Whidbey Island, WA
9. Second Marine Aircraft Wing, Cherry Point, NC (Ten Baiets)
10. MAG-26, MCAS, JacksonviUe, NC (Five Billets)
11. MAG-29, MCAS, Jacksonville, NC (Three Billets)
12. MAG-31, MCAS, Beauford, SC (Three Billets)
13. Branch Clinic, NAS, Kingsville, TX (NRMC, Corpus Christi)
14. TRAWING-2, NAS, Kingsville, TX
15. TRAWING-3, NAS, Chase Field, TX
16. TRAWING-4, NAS, Corpus Christi, TX
17. VQ-l,NAS,Agana, GU
18. VP-1, Barbers Point, HI
19. VP-6, Barbers Point, HI
20. VP-17, Barbers Point, HI
21. VP-22, Barbers Point, HI
22. 1st Marine Brigade, Kaneohe, HI (Three Billets)
23. VSWING-1, Cecil Field, FL
24. VA-127, Cecfl Field, FL
25. VP-16, Jacksonville, FL
26. VP-24, JacksonviUe, FL
27. VP-3Q, JacksonviUe, FL
28. VP-45, Jacksonville, FL
29. VP-56, Jacksonville, FL
30. HS WING-1, JacksonvUle, FL
31. HS-15, JacksonviUe, FL
32. RVAH-3, Key West, FL
33. NAVACTS, United Kingdom
34. Third Marine Aircraft Wing, El Tore, CA (Five BiUets)
35. Branch Hospital, NWC, China Lake, CA (NRMC, Long Beach)
36. VX-5, China Lake, CA
37. VXE.6, Point Mugu,CA
38. Branch CUnic, NAF, SigoneUa, Sicily (NRMC, Naples)
39. VR-24, SigbneUa, SicUy
40. Branch Chnic, NAS, South Weymouth, MA (NRMC, Newport)
B-4
Aerospace Medidne Billets
41. VP-10, Brunswick, ME
42. VP-11, Brunswick, ME
43. VP-23, Brunswick, ME ^
44. VP-44, Brunswick, ME
45. Moi¥ett Field, CA i
46. VP-19, Moffett Field, CA
47. VP-31, Moffett Field, CA
48. VP-40, Moffett Field, CA —
49. VP-46, Moffett Field, CA \
50. VA-127, Lemoate, CA J
51. CVW-2, Lemoore, CA
52. CVW-9, Lemoore, CA
53. CVW- 11, Lemoore, CA
<GVW.14, Lemoore, CA.sr ■ . :.
55. CVW45, Lemoore, CA i
56. VC-5, Kadena, Okinawa i . > •</ , > . . i_
57. MCAS, Futema, Okinawa
58. First Marine Aircraft Wing, Okinawa (Five Billets)
59. First Marine Aircraft Wing, DET A, Iwakuni (Five Billets)
60. TRAWING-1, NAS, Meridian, MS
61. TRAWING-5, NAS, Whiting Field, FL
62. HELTRARON 18, NAS, Whiting Field, FL
68. TEAWING-6,NAii,Pen8«cola,FL
64. NFDS, (Blue Angels), Pensaecda, FL
65. Naval Aerospace Medical Institute, Pensacola, FL
66. Aerospace Medicine Residency (Outservice Training) (Six Billets)
67. VF-101, Oceana, VA
68. VA-42, Oceana, VA
69. CVW-1, Oceana, VA
70. CVW-3, Oceana, V A
71. CVW-6, Oceana, VA
72. CVW-7, Oceana, VA
73. CVW-8, Oceana, VA
74. CVW-17, Oceana, VA
75. HM-12, Norfolk, VA
76. CAEWW-12, Norfolk, VA
77. Environmental & Preventive Medicine Unit #2, Norfolk, VA (AMSO)
78. Naval Hospital, Roosevelt Roads, PR
79. Naval Hospital, Rota, Spain
80. VQ-2, Rota, Spain
81. NARU, North Island, San Diego, CA
B-5
U.S. Naval Flight Surgeon's Manual
82. FASOTRAGRUPAC, North Island, San Diego, CA
83. HC-3, North Island, San Di^o, C A
84. VS41, North Mand, San Diego, CA
85. HS-10, North Island, San Diego, CA
86. VF-121, Miramar, CA
87. VF-I24, Miramar, CA
88. VF- 126, Miramar, C A
89. CVW-2, Miramar, CA
90. CVW-9, Miramar, CA
91. CVW-11, Miramar, CA
92. CVW-14, Miramar, CA
93. CVW15, Miramar, CA
94. Environmental & Preventive Medicine Unit #5, San Diego, (AMSO) (Four BiUets)
95. Branch Clinic, Cubi Point, PI (NRMC, Subic Bay)
96. Branch Clinic, Atsugi, Japan (NRMC, Japan)
97. CVW-5, Yokosuka, Japan (Two BiUets)
98. NAF Misawa, Japan
99. MCAS,Yuma,AZ
100. Third Marine Aircraft Wing DET, Yuma, AZ
6-6
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